Reviewer: Srajan Ebaen, Frederic Beudot & John Darko Financial Interests: click here Source: 27" iMac with 3.4GHz quad-core Intel Core i7, 16GB 1.333MHz RAM, 2TB hard disc, 256GB SSD drive, ADM Radeon HD 6970M with 2GB of GDDR5 memory, OSX 10.8.2, PureMusic 1.88a in hybrid memory play with pre-allocated RAM and AIFF files up to 24/192; Audirvana 1.4.1, April Music Eximus DP1, Esoteric/APL Hifi UX1/NWO-M w. Bakoon BPS-02 battery-powered Audiophilleo 2, Apple iPod Classic 160GB/AIFF, Cambridge Audio iD100 Preamp/Integrated: ModWright LS-100 with Psvane tubes, Esoteric C-03, Bent Audio Tap-X, TruLife Audio Athena, Bakoon AMP-11R Amplifier : First Watt SIT1, FirstWatt SIT2, ModWright KWA100SE Speakers : Aries Cerat Gladius, Boenicke Audio B10, Voxativ Ampeggio Headphone amp : Bakoon AMP-11R Headphones : ALO Audio-recabled Audeze LCD2, Sennheiser HD800, Beyerdynamic T1 and T5p, AKG K-702; HifiMan HE500 & HE6 Cables: Complete loom of Zu Audio Event, KingRex uArt USB cable with Bakoon BPS-02 Stands: Artesania Esoteric double-wide 3-tier with TT glass shelf, Rajasthani solid hardwood console for amps Powerline conditioning: GigaWatt PF2 on amps,GigaWatt PC-3 SE Evo on front-end components Sundry accessories: Extensive use of Acoustic System Resonators, noise filters and phase inverters Room size: 5m x 11.5m W x D, 2.6m ceiling with exposed wooden cross beams every 60cm, plaster over brick walls, suspended wood floor with Tatami-type throw rugs. The listening space opens into the second storey via a staircase and the kitchen/dining room are behind the main listening chair. The latter is thus positioned in the middle of this open floor plan without the usual nearby back wall. Review Component Retail: €2.185 for the base version, €168/ea. for USB, AES/EBU and extended range output transformers

09 November 2012 18:53. "I intended to email you many times before. But due to our move to Maarsbergen and starting production of the Hex DAC, I failed just as often. For us the last few months have been a truly crazy mix of moving to the new location and rolling out first Hex units. Our pre-announcement created massive buzz and preorders. This happened before the production line and measurement facilities were ready. I'd simply never expected this many early adopters for a brand-new model without a single review. With this move my own office now occupies the same building as the production plant. Due to our working relationship going back nearly 12 years, we've decided to cooperate far more closely from now on. This led to the formation of a new entity called All Engineering, a limited liability company which presents me with the necessary freedom to focus on my job as electronics designer. Daily sales support and technical backup services can be handled by as many people as are required. Depending on production schedules this could involve from 10 to 15 folks sharing logistics, production and purchasing tasks. I never anticipated such growth over such a short period of time. Since the sales figures for the Octave, Hex and various OEM commitments have increased so rapidly, we've embedded a new measurement system in the production chain to verify our circuit boards at already a very early stage. This means that during build-up to finished product the electronics passthree different testing cycles which repeat the same measurements on frequency response, jitter, linearity and distortion. I'm really very pleased that the quality and reliability of our product has now reached such a high level.

I intend to send you a Hex for review but we still have a small gap whereby outgoing orders continue to outpace the rate of incoming parts required for production. I'll get you a sample in a few weeks." - Met vriendelijke groet, Cees Ruijtenberg Ruijtenberg's Metrum Acoustics Octave NOS DAC had ceesed its day with quite a bang. In the wake of my Blue Moon award-winning review —recommended reading for the full background—hifi critics like Martin Colloms had found it just as tasty. Forum feedback from owners added waves. Those soon created a small giant killer reputation. Predictable if unsuccessful were speculations about the identity of Metrum's industrial R-2R chips. We're told that they aren't from any of the usual hifi catalogues by AKM, Crystal, Texas Instruments, Wolfson, Sabre & Co but handle data rates up to 15MHz and output sufficient voltage at sufficiently low impedance to require neither a traditional analog output stage nor I/V conversion. [You might decide that the chips look like TI DAC8580 but even if they were, without Cees' glue logic you'd not get them to work properly.

With the latest Hex model, Cees' proven multi-parallel scheme for increased signal voltage and lower noise has gone to16 chips. In that it perfectly mirrors Scott Barry's £6.970 Computer Audio Design 1543 DAC which relies on vintage Philips TDA1543 silicon instead. The fully dual-differential Hex runs eight of its mystery DACs per channel. Over the minimalist Octave that ran four it then adds Lundahl mu-metal core LL1527XL output transformers, costlier parts and more extensive socketry. The latter breaks down as BNC, coax and twin optical inputs, RCA and XLR outputs and optional Cypress Semiconductor asynchronous USB and AES/EBU digital modules.

Cees' 6-layer boards enjoy full galvanic isolation and his 45VA power supply runs three toroids and 18 voltage regulators to separate the conversion circuitry, control logic and USB. Even though the Hex remains a non-oversampling converter, it handles full 24/192 signal on all inputs expect Toslink (24/96). Output voltage is a standard 2Vrms for RCA and twice that for XLR. Slew rate is 35VµS and jitter reportedly remains below 35ps. The upper response limit is 20kHz for 44.1kHz, 65kHz for 192kHz signal. Noise is down a full 130dB relative to a 2Vrms output. Output impedance is 40Ω on RCA, twice that on XLR. Dimensions are a 320mm footprint with 85mm height. Weight is 5.5kg. Perhaps like gun-slinging comic-book namesake Jonah this Hex plays it basic on cosmetics. That focuses it on fast drawing performance over sex appeal which can get old quickly once in the rack. Our Dutch designer's professional roots, bless his heart, still hadn't been usurped by high-end audio's relentless fascination with excess. With reduced wallet cramps, the Metrum Hex joins the ranks of posh NOS converters from 47lab, Zanden, Abbingdon Music Research, CAD, Audio Note UK, Vertex AQ and Concert Fidelity. Here it goes deliberately retro against machines like AURALiC's Vega which upsamples all incoming data to 1.5MHz/32-bit. Modern Sigma-Delta converters can exploit so-called apodizing filters to eliminate the pre-ringing otherwise endemic to their approach. NOS DACs don't suffer that behavior in the first place. If they omit digital filters, they do however retaliate with aliasing noise above half the sampling frequency (22.05kHz for Redbook). To paraphrase Russell Crowe's master and commander, there's much debate over which of the two is the lesser weevil, ringing or ultrasonic distortion. Here one mustn't forget recorded pre-ringing from anti-aliasing filters employed during mastering—which NOS DACs of course can't remove though they don't add to it either—nor this approach's slight treble roll-off. In the end we'll leave the theoretical pros and cons to the engineers both armchair and real and get on with shamelessly subjective listening impressions. But first a few final spells on how to work this hex: "For USB we use a modified OEM M2Tech hiFace 1 for a few reasons. In the past we had several complains of matching an XMOS device to either Mac or PC. From our point of view it thus was too early to implement such a module in our machine. On several occasions we asked people to return their USB interface and Octave DAC only to find that both were running satisfactorily on our own Mac and Windows systems. I am certain that the XMOS device wasn't to blame but rather setup problems on specific computers since I couldn't replicate these issues to establish true cause from the distance. That said, complaints about the original hiFace on either Windows or Mac machines after installing the proper hiFace driver have been exactly nil.

But using this OEM module as a quasi hiFace wasn't our goal. Marco Manunta relies on USB power. This can readily cause all kinds of issues by injecting HF noise into the DAC or forming ground loops which can pick up airborne frequencies from domestic equipment. So we disconnect USB power and feed the OEM module with our 15VA linear power supply which also has complete galvanic isolation from other parts of the Hex. As the data output from the OEM module is useless to the actual data format of our DAC, we add our glue-logic circuit for data 'translation' and buffering which fits below the USB module on the distribution board

Before settling on this particular OEM module over competitors we also verified its digital transparency by feeding it well-known bit patterns from our analyzer. By measuring this pattern once it exited the OEM module we could ascertain that it indeed operated bit perfect. This became another reason to use it. The USB module is optional so people can use their own USB bridge if preferred. From a marketing perspective there's another reason to make it optional. We see two types of customers who might purchase our Hex DAC.

"1/ Music-loving hobbyists. They like to set up a computer as music server and spend much time tweaking it. They need a USB input to run their system. We think this audience makes up about 5%-10% of our total market. 2/ Music lovers. They spend money but aren't interested in configuring a system. This type of customer purchases a DAC to be plug & play. For them the S/PDIF connection is the only action required to make a system run. This is 90%-95% of our market. Here we don't need USB. And that also makes the Hex more affordable

With the Hex we run two discrete converter boards in a master/slave configuration. The master board receives the data from the distribution board at the back of the unit and splits it into left/right-channel data. The right data is fed to the master board, the left data to the slave board. This creates risk for ground loops so we insert a few extremely fast optical isolators for full galvanic separation. Incidentally these particular devices are often used in data transmission systems where they might run 50MHz bandwidth. Both DAC boards are programmable to perform several tasks: 1 - Left mono single ended 2 - Right mono single ended 3 - Left mono balanced 4 - Right mono balanced 5 - Stereo single ended "This flexibility allows use of these boards in many applications and OEM products. Compared to the Octave we improved the max sampling rate to 192kHz. In applications like the Hex where the boards are programmed for mono balanced operation, no direct single-ended output is available.

Enter the Lundahl LL1527XL output transformers. They create the required single-ended outputs. We selected this affordable transformer because many people already seemed bothered by our price tag for the Hex which obviously had to exceed that of the Octave. Especially in the USA the use of single-ended outputs appears less popular. There XLR becomes more important and people wouldn't want to pay extra for a more upscale output transformer they'd not use. For those who want the very best performance from our fully balanced DAC's SE outputs however, we recommend the upgraded Lundahl LL1588 parts. Hence those became our third à-la-carte option after USB and AES/EBU. That's also the transformers your review unit will have."

John Darko standing by in Australia for a second opinion had another question: "My experience with the Octave aligned with many others: that an Audiophilleo or similar USB bridge was essential because the direct optical connection from a Mac/PC was relatively weak. Is jitter/noise rejection on the Hex S/PDIFs superior to the Octave or the same design?

About the direct optical or S/PDIF connection from a PC, I agree that this kind of output is worse than good CD or media players. It is like a Ferrari on a sandy road. There are limits to how much jitter our DAC can handle or we would have had to put in more data-buffering memory. As you probably know data handling in a PC is more or less determined by the processor. There are data-stream gaps at the S/PDIF output. It all depends on other computing actions where S/PDIF never has the highest priority. That said, the Hex jitter rejection is a bit better and <35psec while the Octave was less than 40psec.

When you compare findings, keep in mind that your RCA outputs aren't the same. Your unit has LL1527XL transformers, Srajan's LL1588 with +10dB more headroom and lower distortion. As one of my distributors put it, the 1527 is more romantic and warm—it is also used in the Linn Klimax—the 1588 more real world and closer to the XLR outputs Context. My exposure to DACs has deliberately focused on the <€4.000 sector though exceptions like Meitner's M1 and the all-discrete French TotalDAC factored as well. I don't know what my reference NWO-M DAC would cost were it extricated from Esoteric's UX1 chassis and its massive 'best ever' universal drive mechanism. Chances are it'd be M1 turf or beyond. When the Hex arrived, my DAC chart had the NWO on top followed by the Eximus DP1 and Burson Conductor. Antelope Audio's Zodiac Gold with Voltikus, the Resonessence Lab Invicta and the Weiss DAC2 sat a rung lower. To me the biggest upset of the bunch has been the $1.850 Conductor. Its tone density is second only to the 40 x AKM AK4399 NWO-M with fully differential Lundahl-coupled NOS E182CC output stage yet on bass weight and impact the Aussie box actually eclipses it. On tone-color richness and low-down authority the Conductor is the Audez'e LCD-2 of DACs. It's really quite the step up from its HA-160D predecessor. Though gilding the lily, my ultimate headfi rig at that juncture ran a 160GB AIFF-loaded iPod Classic into the Conductor via the Pure i-20 digital dock, then to Bakoon's AMP-11R in hi-gain mode and the Audez'e.

If the Burson drums out rhythms with tightly packed Q-tips and the Zodiac Gold with pointy tooth picks, the Bakoon splits the difference without sacrificing one iota of the Conductor's tone. Its handling of transients isn't as needly as the tonally far paler Antelope but crisper than the warmer softer-tipped Burson. The 11-R's treble also is more extended and pellucid and the apparent S/N ratio even lower. To put some hours on the Hex, I stuck it into this bedside stack with the iPod in endless shuffle mode to replace the Conductor. Two things happened. Leading edges got more honed—back towards tooth picks if you will—yet timbres intensified further. The at-once-ness of the two qualities often is mutually exclusive. Attack mode which slices air like samurai blades—think hard-hitting loud German techno on 103dB Avantgarde hornspeakers—tends to thin out colors by adding white and turns texturally hard. The Hex resolutely swam against this trend. It was neither lean nor hard. Yes it was rhythmically articulate and keen like tapping glass with long finger nails. But that PRaT precision was followed by highly developed tonal hues and body. This counterpoint avoided all bleaching and prevented high transient fidelity from compromising timbres and textures. When violins and other non-blown instruments exhibit that peculiar singing qualitywhich is otherwise hard to describe but instantly recognizable, I see it as being connected to flow and timing. This the Hex did very strongly. It also 'centered' things back from the leading edge onto the bloom portion without causing even minor fuzziness on attacks. Zing and song if you will even though the second quality very much alters how one perceives the first. There's nothing zingy about the Hex per se. For a while now I've relied on the hopefully intuitive imagery of the textile sound of paper cones and silk domes versus the metal sound of Beryllium, ceramic, magnesium and titanium drivers to point at this core difference. It's between metallic attack mode and how textile drivers tend to emphasize sounds slightly

'behind' the leading edge. In tube terms it's the triode vs. pentode thing, the 2nd-order vs. 3rd-order harmonic emphasis. In those terms the Hex was an equal opportunity omnivore. It did both at the same time. Though writing it out consumes paragraphs and deliberation to find the right words, what I perceived in those moments after firing up the Hex for the first time was sudden, easy and crystallized: 'Aha, that'show it is'. The instrument which combines these two opposing qualities to a similarly loaded degree is the piano. The initial hammer fall particularly when vigorously executed is all about metallic wiriness whilst immediately following is the resonance excitation of a huge cavity which can spell big tone in capital letters. Close miking and Flamenco/Cuban-style hammer playing can exaggerate the percussive elements. Far-field miking and languorous Chopin legatos shift the balance into the bloom/decay aspects. There's a lot of variability hidden in the catch-all 'piano sound' drawer with its makers from Fazioli to Bösendorfer and those endless and wildly disparate player techniques. Yet one telltale mark regardless is the clarity of the hammer falls as they get enveloped inside and thus potentially obscured by the sustain pedal. The Hex simply excelled at nailing the metallic hammer falls and the follow-up response of blooming woody resonance with all its scintillating overtones. That was my first impression. Obviously you can only have that once. Being careful to harvest it properly thus becomes good practice. Far more often than not it's confirmed over the long haul rather than challenged or overwritten. Sometimes understanding what caused first impression takes time. It adds weighting, filling out and value. The actual core insight about the difference—if there is one and it won't change with break-in—simply tends to be sudden and ready-made. In my DAC scheme and hierarchy, the Hex felt like a crossbreed of the Burson sound (bassy, fulsome, warm and dense yet in the Conductor generation also very resolved) and the more lit up, quick, incisive, separated and resolute Bakoon/Eximus flavor. Perhaps it was a well-adjusted

mix of 2nd and 3rd-order attributes. Or akin to SimulClass triode/pentode operation, a term coined by Randall Smith of Mesa Boogie, designer of the Mesa Baron and Tigris amps I helped market for a while. Was the Hex a bit of a best-of-both-worlds scenario perhaps? Clear right off was how it was no mere Octave x 2. It dusted the smaller box by no small margin. This was higher potency juju with appreciably stronger bass, bigger dynamics and more intense magnification power. I was particularly curious how it would fare against the 176.4kHz-capable 16 times paralleled 1543 NOS DAC from CAD's Scott Berry which is seriously more expensive than the Hex. Meanwhile Cees reported how certain hopefuls already found the Hex offensively more expensive than the Octave to invoke Uncle Albert's law of relativity - and that really good things don't come free or cheap. USB reception. Adam Mokrzycki organizes the Warsaw Audio Show and also is senior contributor to the Polish Audiomagazine. His test of 14 USB bridges netted the following ranking: Matrix 24/96 - 60; TeleVox 24/96 - 65; Hegel HD2 - 65; Musical Fidelity V-Link II - 75; Halide Design The Bridge - 80; M2Tech HiFace Evo - 80; Stello U3 - 85; M2Tech HiFace Evo + Evo Supply - 90; JK SPDIF Mk3 - 90; Audiophilleo 1 - 95; Empirical Audio OffRamp Turbo 5 - 95; dCS U-Clock - 95; M2Tech HiFace Evo + Evo Supply + Evo Clock -– 100; Scarlatti CD/SACD transport - 100. Subsequently he reported that with the new Pure Power battery supply, the Audiophilleo became "one of the best if not the best S/PDIF converter I know. Apart from those I reviewed above I also tried the über-expensive Soulution 590 which was average at best."

My Audiophilleo 2 run off Bakoon's BPS-02 battery supply organizes internal power delivery differently from Audiophilleo's own battery. Even so the improvements I hear over plain USB power suggest that in Adam's scheme it still would make his top 3. It was sensible to compare my battery-fied unit to Cees' modified hiFace 1. Would external USB reception be mute now or remain performance enhancement as it is over my NWO-M's internal hiFace 2? For a fully balanced chain to give the Hex its intended context, I ran AURALiC's Taurus Pre and ModWright's KWA-100SE with Zu Event XLR cables

Using The Secret Trio: Soundscapes (your chance at a quasi Taksim Trio reunion if rumors are true that there won't be seconds) the outcome was

unexpected if most interesting. Hex direct placed greater emphasis on the 3rd-order transient mode. This became particularly noticeable on Pinarbasi's qanun plucks that exhibited more lightning-y attacks if we borrow from the talking rat of Ratatouille. But even on a whole this particular presentation simply felt

more quicksilvery and so also a tad leaner. The Audiophilleo played it stronger on 2nd-order tone mode. This enriched the augmentation of timbres particularly when oud, clarinet and qanun run parallel motifs. It also mellowed the sense of speed to feel just a bit more relaxed. Transitioning to the Resonessence Labs Concero with Tombo Trøn cable—Audiophilleo's direct connection doesn't work with the Canadian box because all

its socketry is on one end—shifted just a bit deeper into these 2nd-order attributes and got a degree or two warmer still. All of this was only minor seasoning and very similar to adjusting the operating point of Nelson Pass' SIT1 monos which he explains in these exact terms. The upshot for prospective Hex owners intending to do USB seems simple. Metrum's optional USB module competes directly against $600 external boxes which in most cases will still need a quality S/PDIF cable to increase costs further. Here going offboard is a tuning feature like rolling tubes or swapping cables but on magnitude far more narrow. If at all I'd think of it as a last resort once everything else in a system has been sorted to complete satisfaction. One then simply plays with minor final adjustments. And one is fully prepared to admit that how one responds depends on mood and material to fluctuate possibly from track to track. So why even bother? Integration all in one box is far more elegant.

2nd opinion from the dark side - John Darko of digitalaudioreview.net.au chimes in: My current main system comes with less wallet damage than Capt'n Sraj's - Magnepan $600/pr MMG powered by an AU$1.900 Audio-gd Master 10 integrated pumping 500 much needed wpc into the Maggies' 4-ohm load. Despite being the priciest unit in the chain, the Hex was in no way out of place in more wallet-friendly company. This amplifier/loudspeaker pairing has little trouble exposing upstream changes. A harsh truth that nearly every digital audio newcomer must face? Stock USB on many DACs just ain’t that good. So long as these more washed-out sounding USB implementations abound, the likes of Audiophilleo, John Kenny, W4S, Stello and KingRex (et al) will be called upon for their USB-S/PDIF bypass boxes. Start at the end . The optional USB implementation on the Metrum Hex is a knockout. It’s a modified OEM board from M2Tech which in turn is based upon the popular Mk1 hiFace. Inside the Hex main man Cees Ruijtenberg has the M2Tech board up and at 'em with a 15V linear regulated power supply. End-user M2Tech drivers are required to get up and running and bring with them the usual caveat of all Mk1 hiFace devices: there exists an audio lag when watching movies and TV. I confirmed this to be true. Why not a Mk2 hiFace? "We checked several USB designs and found it hard to verify standard products as thing will be different when built into the DAC especially when exacting our standards of how to match such devices to our electronics. For instance, the hiFace Mk2 (XMOS) is great for the money but surpassed by the hiFace Mk1 using separate linear regulated power supplies instead of USB power. Beside this we have deployed another receiver section in the Hex having lower jitter. The sum of these properties made us decide to use a modified OEM version of M2tech together with our electronics. Further it can be hard to find the best device. A cable for instance can be great for one type of interface while the score is low using another brand interface on the same cable. Another problem was that the fact that when no drivers are necessary for Macs it sometimes lead to errors (don’t ask me what people are doing on their machines!). We have tried to avoid this until such a time that this technology is rock stable and here the original hiFace was the most proven contender." To best extract many a DAC’s core fundamentals in the <$3K sector, a USB-S/PDIF converter's intervention is required more often than not. But not here. The Hex's internalised USB option held steadfast against off-board devices with an ever-so-slender edge in the broadest inner-illumination avidity whereas external S/PDIF appendages from KingRex and Wyred4Sound stirred in a hint of brown sugar for slower fatter transient edges. Direct USB was peachy keen, cooler and leaner than indirect data transfer. Direct-to-Hex USB also was fast and more wide-eyed and vibrant than any of my bypass bricks. These deltas were small but underlined the emerging truth that USB doesn't have to be a bare-minimum connectivity hurdle jump. Cees - terrific job here.

Many prospective buyers might initially balk at the cost of Metrum's USB option (€168.00/~US$220). Think about it more carefully then. Once a minimum $300 is factored for a good off-board USB converter topped up with a $100 S/PDIF cable, the Metrum’s USB board begins to look increasingly attractive. There’s no Mk2 hiFace shortcut here. Powered by dirtier 5V from a host PC, that $200 device couldn't hex the Hex. Elijah Audio’s BPM splitter cable and the battery-pack UPower from KingRex soften the sound but burden one’s spend with an additional ~US$350. If you don't go for the onboard Metrum USB option, hold on to your converter. Like the Octave, the S/PDIF inputs of the Hex are transport-sensitive. Cees explains: "About the optical or coax connection directly from PC, I agree with you that these kinds of outputs are worse compared to good CD players or media players. It's like a Ferrari on a sandy road. It's not usual to combine such expensive equipment with relatively cheap gear. So there are limits to the DAC's jitter handling. We'd have to put in a bigger piece of memory to buffer the data. As you probably know the data handling in a PC is more or less determined by the processor so there are gaps in the S/PDIF data stream... Jitter rejection with the Hex is <35pSec while the Octave is <40pSec. Software playa . On a Mountain Lion'd MacMini, the Audirvana+ beta 1.3.9.11 wouldn't talk to the in-house Hex USB implementation. Audirvana's integer mode isn't possible with any Mk1 hiFace but even disabling that check box still couldn't coax sound. A+'s progress bar showed the track pre-load but the playback point marker refused to budge [affirmative also on my end but rebooting the non-beta version fixed it - Ed]. Odd. No such dramas occurred with Amarra [or PureMusic 1.88a - Ed]. Back to a non-beta Audirvana+ (1.3.5 sans Integer mode-tick box) and everything was tickety-boo once more. Later in the review period Audirvana + 1.4 bowed. Deselect direct mode and sound! Monster, DVD-A rip. 24 bit. What's the sampling freq, Kenneth? 88.2kHz. Receiving a mixed reception at its release in 1995, this latter-career entry from R.E.M. has stood the test of time. Peter Buck's buzz-saw guitars weren't as transient driven as via the MyDAC. The Hex exposed an abundance of timbral information obfuscated by the Micromega unit. Strong suits from Metrum's statement unit were tonal density, timbral finessing and decidedly unexpected warmth. More specifically, warmth communicated as humidity rather than direct sunlight. The single-ended outputs on my review unit differed from Srajan's. Cees elaborates: Keep in mind when using the RCA output that both DACs aren't 100% comparable. The one I sent you has the Lundahl LL1527XL while Srajan has the LL1588 with +10dB more headroom and lower distortion. As an agent for me described, the 1527 is more romantic and warm [it is also used in the Linn Klimax] but the 1588 is more like the real world and closer to the XLR. Whilst your unit was in transit we evaluated the 1588 and decided to deliver both options". The takeaway from this takeaway meal is that you have seasoning options at order time. On a balance beam . I next switched to balanced connections as the Audio-gd integrated allows for it. The incoming XLRs from a Peter Graves cable of Adelaide's Grave Science company subbed for Chris Sommovigo's Black Cat Morpheus interconnect. Here music played into thinner air. Tonal operating temperature dropped a degree for a slight improvement in detail magnification and an upward click in bass definition. I'm cognisant how these deltas could be simply attributed as much to the cable brand switch as the connection mode change. Either way, for the electronic programming that underpins Liars'WIXIW the balanced routing was preferred. Single-ended Lundahl LL1527XL coupling had the edge—by a nose—with guitar-shred records like the aforementioned R.E.M. as well as Neil Young & Crazy Horse's Psychedelic Pill. Here I dug the Hex's nod to warm stickiness. It's not what I heard in the Octave last year which itself was slightly glassier, leaner and more diluted than its bigger/badder brother. I heard none of the Octave’s glassy shimmer from the Hex. The horns on Thomas Dolby'sAliens Ate My Buick were emphatic and shapely. Blat by the butt load. The electric bass that underpins "The Ability To Swing" was abundant with textural information and sufficiently weighty that the song was driven pendulously by its core - er, swing. Being a late 80's production, this record often displays hints of that era's shiny-polished production glare. Not with the Hex where thicker air plumped and softened the delivery without pulling a veil over details. The Hex’s window on the world was squeegee-clean. Very, veryimpressive. Pressure and poundage meant that music didn't hang suspended mid air but was tightly anchored. An abundance of tonal heft ensured that Neil Young & Crazy Horse's epic "Ramada Inn" lurched low and tight across the room. Soundstage illumination didn't just rain down from house lights above, the players themselves lit up the song from within. Microdynamic shifts were rendered with similar inside-out pressure. The shape of Young's guitar was drawn first with transient edge, then filled with deeply saturated tonal colours. This quality alone marks the Hex a hero in its own price range. None of these attributes hindered the Hex's need for speed. It remains whip-crack fast. Elasticity with urgency. Shake and bake . A non-audiophile buddy has a phrase for certain techno tunes that wallop hard below the belt and sugar sparkle up top. He calls this quality "Tinkle-Beef" – the perfect description for the Metrum Hex then. The Octave could err toward leanness but the Hex fills you out with flesh and colour. Think sparkling mineral water flow for Octave but champagne cascade for the Hex. The latter spills with a broader spread of flavours and greater body.

Icing . Balanced connectivity and the ability to run sample rates up to 192kHz make this already compelling proposition a damn-near must have. It’s a new reference for this fellow. Time for team Metrum to pop a cork

Footnote : The get-out-of-jail-free card played by reviewers unable—or unwilling—to spill forth with comparative information is to seal the review envelope with the cliché that Product X "competes with units two or three times the price". I shall not insult your intelligence with the same here. A head-to-head between Product Hex and the Auralic Vega is penciled in for early 2013. The resulting commentary will be published on Digital Audio Review

3rd opinion from Frederic Beudot: Typically when three reviewers listen to the same piece of equipment in vastly different systems, the results rarely overlap completely. Components express their strengths and weaknesses differently depending on context. Couple this with significantly different music preferences and listener biases and the reader will be lucky to find a few common threads from one opinion to the next. Nonetheless opinions sometimes converge to focus on dominant qualities a component will express regardless of environment. We ran into this a few years ago when three of us described the effects of ASI Liveline cables in almost identical terms. With Metrum's Hex we now have a rerun of sorts. My current system begins with a dedicated Mac mini running either PureMusic or Audirvana+ into a Burson Conductor as DAC/preamplifier driving a First Watt F5 into a pair of Ocellia Calliope .21 Twin Signature review speakers All cabling is Ocellia including USB. With the Hex not offering variable outputs I use the Conductor as preamp in its lowest gain setting when listening to the Hex mostly via USB. The modified OEM USB module is incompatible with Audirvana's Direct mode. I initially experienced the same issues John and Srajan did when A+ 1.3.10 refused to play ball with the M2tech driver even with Direct mode disengaged. Reverting to an older version pre Direct mode or updating to A+ 1.4 then disengaging Direct solved the issue. Yet I never felt that the combination of Hex and Audirvana gave the best results or provided the fullest expression of what the Hex could do on tonal rightness and flow. Unlike with the Burson Conductor where A+ with restored Integer mode remains my absolute reference for microdynamics, I consistently preferred PureMusic for the Hex. One small issue arose the first night. The Hex's USB processing involves an about 1-second delay to where playing a movie from the Mac mini has the sound arrive about a second behind the image. This wasn't exactly a crowd pleaser at casa Beudot. My family was headed into an all Batman night to force me to reconnect the Burson urgently as that suffers no such delays via USB. For video-less systems there's no issue without any visual reference. With video the USB input's generous buffer to better manage computer-induced jitter makes said latency a non-starter however. Thankfully there's a relatively easy workaround for somebody like me who insists on using the Hex also for video: connect the computer via optical and USB. In OSX Lion it's easy to then set up the optical output as default for movies and PureMusic or Audirvana+ to short-cut optical in favor of USB for music. All this gets done upfront once and from that point forward you only have to select the appropriate input on the Hex—Toslink for video, USB for music—and voilà, the best of both worlds. Back to the Hex for musical enjoyment, it became the DAC which thus far came closest to the full immersion I feel when listening to vinyl and actually many times exceeded it. With the Ocellia speakers on loan, it was very easy to lock into two very critical elements of music reproduction - tone accuracy followed by the balance of leading edge to decay. I typically find that the most engaging systems get those two things right. Other factors like microdynamics and realistic staging also matter to me but if the first two aren't spot on, the next two won't tip the scale. The Metrum Hex excels at the first two like no other DAC I've heard and throws an impressive sense of flow into the bargain. Starting with Marc Minkowski's latest recording of Schubert's Symphonies with Les Musiciens du Louvre—a superb version on period instruments by one of the most dynamic period ensembles in Europe—the Hex simply eclipsed the Burson on the natural tonal qualities of the various instruments. Period instruments often sound shrill on digital but rarely so in vinyl. I believe it's because those instruments are more heavily weighted on the attack with less harmonic decay than their modern counterparts to often cause an off sound whose initial impulse is imperfectly reproduced. The Hex proved capable of lightning-fast transients with full tonal development and decay to provide these period instruments with their true musical signatures - neither aggressive nor mellow but sharp and complex.

This was never as obvious as on Fabio Biondi's Vivaldi Concertos for Mandolin which I never truly appreciated because the mandolins were excessively biting and completely missing in harmonic development like a poor harpsichord recording where the strings sound pinched without the vibrations of the soundboard. Through the Hex the mandolins came completely alive with actually more energetic initial dynamics than before but without missing the sonic body. I'm not saying that Burson's Conductor misses either but it does not succeed quite as well in merging these elements into a realistic instrument whereas the Hex does. It is a subtle difference but one that was consistent across all discs I listened to. The Burson sounds like two pieces very closely patched together and matched, the Hex sounds like one whole musical event as though there was no qualitative difference between leading edge—which is sharper and cleaner than any cartridge I own—and decay. You can apply that description across the board from Alison Balsom's trumpet, Tchavolo Schmitt's guitar and Gustavo Leonhard's harpsichord to Bela Fleck's banjo. It held true in every situation. The initial impact or attack was cleaner and sharper than with any other source I've owned or reviewed (including the renowned Esoteric X03SE and P/D05) whilst providing more tonal followup than even the Burson and significantly more than the Esoterics. All this talk about leading-edge sharpness and transient dynamics could leave you thinking that the Hex is clinical and analytical. Not. The Hex sounds extremely rich and organic without any kind of voicing artifice. Its top end is actually more extended and refined than the Conductor which already was a huge improvement over the HA160D The other area where the Hex surprised and delighted was its ability to accurately recreate the recorded environment. I can usually point to one or two features a source does well—width, some level of ambient retrieval or even depth—but the Hex did it all to a quite exalted level: width, depth, hall ambiance, layering of instruments and holographic presentation of soloists. When I earlier pointed at certain aspects where the Hex bested my vinyl setup, that's exactly what I was talking about. Listening to Harnoncourt's recording of Mozart's Dominiscus Messe K66, the Arnold Schönberg Choir simply spread in front of me as wide and deep as my room allowed John and Srajan reported on how the Hex fared on modern music and electronica. I really focused on those details which should matter to folks who primarily enjoy acoustic music from early Baroque to large romantic orchestral pieces, from violins to soprano voices. Unless you're replacing a very advanced digital piece from the likes of MSB or Esoteric for example, I can't imagine that you wouldn't be completely seduced by the Hex. And even in those cases you may well find that the qualities of a superior NOS DAC like the Hex exceed the benefits of more traditional digital implementations even if I recently did hear the new MSB Analog DAC which may well challenge the Hex for most analog-sounding DAC at an obviously quite steeper price. Speaking of the Hex's NOS status with its usually associated limitations, throw away most your preconceptions. The top end of the Hex is not rolled off but extended and very lively in a non-offensive undistorted fashion. I don't think I need to dwell further on its ability to resolve the finest nuances of the musical fabric which it does in spades but unlike the Esoterics and MSB without projecting or showcasing this ultra-high resolution. It simply exists as part of the music. The Hex is less impressive or showy—pick your perspective by whether you enjoy this reinforcement of textures or not— but to my ears more natural. Like all other NOS designs I have heard, the Hex excels at flow so that compared to filtered Delta-Sigma DACs all sense of digital 'edginess' is eradicated. It's a phenomenon that has always baffled me given that NOS designs in theory can't reproduce a perfect sine wave to create stair steps instead. Yet they sound more free-flowing to many folks including me. This reminds us again that the factors impacting music perception are not yet fully understood and that dynamic behavior and pre/post ringing may play a far greater role than initially believed. One area where the Hex may not be quite as good as the very best is bass heft. It does go deep with great texture; indeed bass sounds very organic and natural but the Ocellia speakers being a little short in upper bass impact and power reveal restraint in that range where the Hex was clearly less gutsy than Burson's Conductor. Primarily kettle drums sounded a little more shy over the Hex. You could well challenge me as the Ocellias being less endowed in said range might indicate the Burson to be somewhat over-zealous whilst the Hex could be perfectly balanced. Personally I'm still debating whether the Hex will stay or not. It is superior to the Burson in almost every single way that makes the difference between very good playback and suspension of disbelief but also comes at a steeper price (though still reasonable in the grand scheme) and at the cost of limited functionality. That's probably the only area where I would fault it. I know that its designer targets people who mean to upgrade the digital section of their CD player or digital front end but a growing portion of audiophiles are going to 'integrated' front ends which combine digital and preamp functions without giving up on analog attenuation. That's where the Burson Conductor, Eximus DP1, AMR DP777 and MSB Analog DAC come to the fore to name a few which morph from just DAC to main control center. The Hex doesn't fit such a setup. I thus hope that one day it will become available with an optional analog section providing analog inputs and volume. In the meantime I will continue to enjoy its exceptional musicality and burn through as many discs as I can while I can

AES/EBU'd iPod: Via Van den Hul's purple 110Ω AES/EBU Pro a Cambridge Audio iD100 talked to the Hex to have meflummoxed over how good streaming 16/44 AIFF files from a 160GB iPod Classic was. My fully optioned-out quad-core iMac with 2TB/256GB HDD/SSD requires the intervention of PureMusic 1.88a or Audirvana+ 1.41 to bypass a number of computing activities and optimize the sound via memory play. The music-only battery-powered iPod with its barely-there OS sounded terrific getting hex'd as is. Now my exposure to the digital AES/EBU standard is exactly 1 as this was my first foray. All I'll say is that the same dock's S/PDIF route via an equivalently priced Veloce link was clearly inferior to perhaps suggest higher transfer jitter; and that if you own an iPod and iD100, using the latter's XLR output will be educational with a DAC like the Hex that's got the equivalent input socket. Upsampling an NOS DAC : Like Frederic I loved how PureMusic's 64-bit software-based NOS-type upsampling to 176.4kHz worked with the Hex. Sonically PureMusic 1.86 had been bested by Audirvana+ somewhere into the latter's 1.3.9 beta. With 1.88a Channel D had caught up again. Whilst I'm technically too dim to explain why upsampling the NOS Hex should work so well—and what it might imply about our collective attempts to explain why NOS DACs in general can sound so good—I'll merely suggest that should your music player of choice afford you the option of integer upsampling, give it a whirl on the Hex. It might just suck you in. If it plain sucks, 'twas a free lesson.

XLR vs. RCA : With many so-called fully balanced preamps running single-ended volume controls to involve conversion of balanced inputs, ultimate statements on the Hex's two outputs seem impossible. So much depends on how the following preamp or integrated amp treats their balanced inputs. Extrapolating my results from running the AURALiC Taurus Pre, the Esoteric C-03 and the ModWright LS-100 preamps with equivalent Zu Event RCA and XLR cables, my final hunch is that the balanced outputs of the Hex might have a minor edge on jump factor. That said, I decidedly encountered no RCA warmth of the sort John described when using the 1527XL transformer option. The 1588 upgrade seems delightfully free of the softening/fattening effects one can incur with coupling transformers 16 x 1543 vs. 16 x mystery chips or £6.990 vs. €2.521 : CAD's 1543 DAC sounded as though the Hex were preceded by a Concero USB:S/PDIF converter

to represent more 2nd-order tone bloom over less 3rd-order attack separation in general, on quantity about two Conceros worth. In addition the transformer-coupled Philips chips also shaded the treble to be less lit up. This was particularly obvious on struck triangle's diminished fire and dynamic cresting as well as lightly tinkled upper piano keys. It conveyed less ambient air and spiderwebby stuff. In short, the thrice-priced USB-only British machine felt deliberately groomed for traditional NOS virtues. It sounded generally softer/smoother and in particular slightly hooded in the upper treble to suggest a denser slightly midrange-y mellower take dialed for flow over adrenaline. The Hex exhibited none of the breed's trademark treble softening. It was more impulsive on attacks and more elongated on harmonic decays. I had earlier

referenced that simultaneity as zing and song, 2nd/3rd-order simulclass or a crafty triode/pentode mix. John had dubbed it tinkle beef. Frederic described it as more energetic initial dynamics without missing sonic body. Regardless of system or personal preferences, the Hex had behaved identical for three reviewers to reveal its signature or core sonics as the guaranteed traits that'll survive translation no matter your system. 16 x mystery chips vs. 40 x AKM AK4399 + tubes . Alex Peychev's completely rebuilt Esoteric UX-1 called APL Hifi NWO-M run as just DAC with my Audiophilleo 2 USB:S/PDIF converter and Bakoon's BPS-02 battery supply split the difference between Metrum and CAD. It mirrored the Hex's elongated decays and ambient illumination but didn't equal its leading-edge incisiveness or speed. Observed from our second angle, it inhibited the mellower gestalt of the 1543 'smoothie' DAC with its creamier tone but still managed the added more modern treble brilliance for enhanced sparkle. On price the older NWO-3.0GO rebuild demanded $19.000 on top of providing Alex with an Esoteric deck. It's fair to say that Cees Ruijtenberg's pricing of the Hex exemplifies Dutch thriftiness at an Olympian gold medal level. To pull John Darko's get-out-of-jail-free card, the Hex competes with converters well north of thrice its sticker represented here by the CAD and APL machines. In a system celebrating typical ceramic driver sound, the Metrum DAC's frontal acceleration on transient microdynamics could conceivably cause a bit of a cold shower. It might overemphasize musical staccato/pizzicato elements over their legato counterparts to sound too prickly. In a vintage paper-cone system the Hex should be a much-needed shot of adrenaline and caffeine. In a well-balanced system of the sort most seasoned audiophiles likely aspire to after having explored the various byways of the main audiophile highway, the Hex loads up the scales of blister and tone equally to do both non-choppy flow and non-smoothed directness. All this operates on a very high level to be fully compadre in mature systems where each component costs $10K. Conclusion. If the NOS Hex DAC were a 300B, it'd be no Western Electric or Full Music SE but a Synergy Hifi. It's most relevant to stress that the digital NOS tag in this instant requires the prefix of modern. Not only is the silicon of choice not the usual sort exploited for this approach, the resultant sound isn't the same. What it shares is temporal fluidity as the opposite to choppiness. Where it differs is not sounding slightly muted or overly smooth. It does spatial illumination full of air and light to champion very high resolution, then puts rhythmic alacrity on a very tall pedestal. It's not just about tone and languorous fades but also the visceral excitement of percussive exactitude. It's a bit of a bridge then between the classic NOS and modern Delta-Sigma sound. The perfect music track to envision this would be a well-recorded Claude Challe Buddha-Bar studio production with artificial but expertly layered-up ambiance including anti-phase effects. Think deft club groove distributed across multiple percussionists panned wide left, right and center. They energize not only various synths but a large array of bona fide Tibetan singing bowls, gongs, glockenspiels, triangles and cymbals stroked, brushed, tapped and twirled. There's a bassist handling a walking line with regular popped and slapped accents and a breathy songstress. It all makes for a unique mix of loaded harmonic sprays, endlessly dying fades, snappy instantaneous beats and exceptionally well-sorted deep space. Full-featured as a DAC though lacking volume control, the 24/192 asynchronous USB implementation not only competes on the level of an Audiophilleo 2 or Resonessence Labs Concero, it being dissociated from PC power means that effective though added-cost battery power tweaks become redundant. As Gene Hackmann has often been called the consummate actor's actor, the Metrum Hex is the archetypal engineer's DAC. It's very well engineered yet completely unpretentious on finish or price. It's a simple ¾-width box with standard rather than bling-thickness fascia yet the underside of the cover is lined with a bituminous plate to prevent ringing. To prevent redundancy of a different ringing, the AES/EBU and USB input modules are à-la-carte options and very fairly priced should you want them. In all the many ways which I'd consider relevant to cost-conscious shoppers pursuing maximum performance, Metrum's Hex is a true statement DAC. Going Dutch has never sounded this posh. It's also the first time one of our awards was shared between three writers who saw perfectly ear to ear...

Metrum Acoustics comments : First a big thank you for this award! It was quite unique that in three different places around the globe the Hex was tested simultaneously and I'd already mentioned to John and Frederic that it makes us proud and also a bit shy that we received so much attention for a second time. Also thanks to Samuel Furon in Canada who introduced the Hex to Frederic which was a surprise for me. One and a half years ago I told you that it was probably time to create a second production facility and that's exactly what we now did in Maarsbergen. Hopefully we can manage production of the Hex without needing to create a third production facility :-) Anyhow, all this attention to our products gave us an nice place on the hifi map and opportunity to create more products which hopefully will have the same success as the Octave and Hex. For both analog and digital we have some exiting ideas for the future but like good wine those need time to fully mature. Again many thanks to your entire whole crew! Cees Ruijtenberg