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John Kenny JKDAC32 review (M2Tech Hiface + PCM5102 + LiFePO4)

I know, I know. I keep banging the drum for (good) USB-S/PDIF converters. My recent ramble through a world of digital transports seemed to resonate with a number of readers. Good! USB-S/PDIF converters are near-essential in juicing every last sonic vitamin and aural nutrient from one’s DAC. I’ve long advised readers who email in that they might find more satisfaction in aiming their DAC sights lower so that their budget can accommodate an Audiophilleo or a JKSPDIF or a Stello or whatever. At the DAC airport, these widgets’ function is twofold: passport control (data clocking) and customs clearance (power-supply clean-up).

However, my “Dear John” responses aren’t based on theory alone. I’ve not heard a budget DAC whose performance wasn’t lifted by the Audiophilleo2 or JKSPDIF MK3. Don’t take (only) my word for it. Ask any Metrum Octave owner what their toy sounds like without such a converter tidying up its S/PDIF diet. Don’t listen to their response; just watch their face grimace as they start talking.

January 2012. A wave of clocker amelioration is already upon us: battery power, off-grid listening. The KingRex UD384 can be piggy-backed by its UPower Li-ion pack and Philip Gruebel at Audiophilleo recently announced a PurePower VLN battery unit.

A few DAC manufacturers are also waking up to vanilla receiver chips not being good enough for the more demanding/discerning digital audiophile. The guys at ESS continually tout the jitter elimination of their Sabre chips but is “zero jitter” attainable? Is it really that easy? I doubt it. Minimisation is the name of the game. Alex Yeung’s Eastern Electric Minimax Plus features circuitry licensed from M2Tech and (boy from Oz) Mike Lenehan now stuffs a battery-fuelled Hiface into each of his all-new-and-improved PDX boxes.

John Kenny is a seasoned member of the DIY audio scene. He’s been modding Hifaces for a while now, adding battery power into the mix to create the JKSPDIF (now at MK3 iteration). It’s one of the best bang-for-buck computer audio ‘transports’ around. Asynchronous USB propaganda-ists will like see this as yet another win for their team. We should be wary of such campaigning. Async isn’t necessarily the fix-all we computer audio folk require. I remain unconvinced by the stock standard Hiface and yet John Kenny’s inclusion of the same M2Tech device in his recipe makes for an altogether more convincing listen. Go figure, remain pragmatic.



The ESS Sabre 9022 silicone possesses its own (micro) output stage such that 2V comes straight off the chip. No output stage is required within the broader boxed implementation. John Kenny has already realised the potential here by I2S-wedding his tried and tested battery-modded Hiface to the aforementioned ESS chip. The I2S pipe between Hiface and DAC chip means clock information and audio data each have their own travel lane. The result? The JKDAC (500Euros), a USB-only decoder that offers a souped-up input stage as well as off-grid listening.

In November 2011 a sibling arrived: the JKDAC32 (500Euros). Same Hiface input, same LiFePO4 battery, same I2S bridging, different DAC chip. This time we get a Burr-Brown/TI PCM5102 “for those that prefer something other than the sound of an ESS DAC chip”, says Kenny. The charging functions thusly: turn ‘off’ to recharge, turn ‘on’ for listening (and battery depletion). A single blue LED indicates operation and a full charge will give up to 12 hours of listening. Ample for most. And then…

Auto-charging update – March 2012. John Kenny announced that his units – the JKSPDIF, JKDAC and JKDAC32 – are now able to be trickle-charged whilst listening. No longer any need to flip the off switch for a top-up.

“The JKMK3, JKDAC & JKDAC32 now have an optional setting to charge the batteries while at the same time listening to music (without any sonic degradation). This takes away any concerns some have over using batteries. There is no shortening of their lifetime (20 years) using this form of recharging.”, says Kenny.

“Another new feature is that the charger can now take +5V as it’s input which opens the way for using a spare USB port for battery charging – just requires a USB cable with 2.1mm plug on it’s end. When using a laptop this means a completely portable, untethered operation is possible which gives high-end sound.”

Neat.

M2Tech’s Hiface drivers are required for this device to function on Windows and OS X. Attention iOS/Linux users: there is nothing for you to see/hear here. Once the driver is installed, the JKDAC32 presents itself to OS X Snow Leopard as ‘M2Tech Hiface’. Then comes the wrinkle. The JKDAC32 can handle up 32/384 if the M2Tech Young driver is used.

John Kenny explains: “The Hiface itself has always used a 32bit channel as its pipeline. This simply gets stuffed with zero bits when processing 16bit or 24bit audio. It is limited to 24/192 by the Hiface driver (on the computer side). When using the Young driver, it can pipe the full 32bits at 384KHz speed. If you use I2S to communicate with a 32/384 capable DAC chip (PCM5102), you have a fully working, no tricks 32/384 working DAC.” Audirvana confirmed there no gaps in sample-rate handling either: 44.1, 48, 88.2, 96, 176.4, 192, (384) are all covered.



Glitch-hop. As mentioned in the JKDAC32 user manual, even when standing to attention for the operating system the unit doesn’t always parse audio bits. On a few occasions during the review period, the JKDAC32 showed up in sound settings as expected, but no sound came forth. A swift up/down manoeuvre of the front toggle-switch usually zapped this gremlin. Slightly annoying but not a deal-breaker by any stretch.

vs. Rega DAC (AU$900). The JKDAC32 and its British counterpart share some qualitative similarities. They both lean towards the organic end of the spectrum. They both put overall musical coherence and PRaT ahead of detail extraction and top-to-bottom frequency extension, the Rega being warmer overall by way of a plumper lower-midrange. The Rega’s also a little more lively in the top end. The kicker being that the Rega demands the JKSPDIF (or similar) to run even-Stevens with the JKDAC32.

A run through Lampchop’s Mr. M, first with the JKDAC32 and then with the Rega DAC: without USB-S/PDIF converter appendage – and fed via its own USB input – the Rega DAC sounds comparatively tonally bleached. Kurt Wagner’s vocal body is thinner via standalone Brit than the all-in-one Irishman. For a record that seduces with hushed tones, an inky-black background is critical mood enhancer. The JKDAC32’s battery infusion wins hands down here. Running its USB direct into the Mac Mini, the Rega’s background is infected by a soupçon of hash-fizz.

vs. JKDAC (Sabre). They might look identical, but they sound sound the same. The Sabre original materialises as the better trawler of deep detail. It extends further at both frequency extremes: a bass that swings wrecking-ball low but a top-end that’s crystalline and vivid. Smooth or refined it isn’t; there’s little evidence of vapour-trail decay (for which you’ll need to BYO tube amplifier). Like many ESS-chipped decoders, the Sabre-d JK sounds lit-up by brilliant sunshine and is highly caffeinated. It’s pure Sydney: in your face, fun, brash, thrilling…and (sometimes) tiring – the deep detail carve skirts the edges of listener fatigue during longer listening sessions. Redolent of MSG as a food flavour enhancer, the initial wow-factor of that extra tongue-zing ultimately morphs into an inner-detail hangover. Or exhaustion. Or both.

The JKDAC32 is pure Melbourne: cooler, wetter, more cultured, smoother, more refined. It does’t draw attention to itself and is altogether more easy-going. Instrumentation is served up as more congealed – a thicker soup and with less spice.



I took this Kramer vs Kramer into the can courtroom – AKG K-702 fed by a Burson HA-160. Pink Floyd’s The Wall climaxes with “The Trial” – a cacophony of horns, chanting, footsteps, explosions and screams – which in turn collapses into the close-mic’d and sinister “Outside The Wall”. The JKDAC cleaves more space between the complex layering of the pen-ultimate tune. It also amps the intimacy of Water’s whispered vocal turn on the closer. “After all, it ain’t easy, banging your heart against some mad bugger’s wall”.However, my preference leant very much towards the JKDAC32’s more reserved take. There isn’t the wide-eyed detail wonderland of its brother, the truncated “Isn’t this where we…” that brings the listener full circle isn’t quite as easily heard. In broader terms, the JKDAC32 stirs in a thickening agent and a few drops of water for a sound that’s more moist and richer.

Back to open-air listening – Sansui AU-417 pushing ProAc TR8s – and the JKDAC32 evinces with a deeper soundstage. Curiously, it also seemed not as wide as its Sabre forerunner. I pulled on Kenny’s coat about this.

“You have to be careful here – increased depth in the sound stage signifies a better focus & placement of the various elements in the sound field i.e more precision & resolution. A wider sound stage can often be a psychoacoustic effect that certain phase distortions give rise to. Yes, this can sound pleasing but again is it on the recording? Just something to think about.”, came his reply.

Direct connect. A few forum brothers had reported that directly connecting the JKDAC32 to one’s computer sounded considerably better than having it USB-cabled. Say what?. A shorter signal path, yes, but to do so required a couple of eBay-sourced connectors (details here) – what quality those? I’d brought a large serving of cynicism to the table on this one…

Caetono Veloso’s and David Byrne’s 2004 performance at Carnegie Hall has recently seen CD issue. Here, Byrne’s sinister Life During Wartime is stripped back to acoustic first principles. It still works. Cello thrust maintains the momentum and drive of the song; and said thrust is richer, more alert, more *there* without an intervening QED USB cable (AU$40). Direct connect has more jump factor and superior micro-dynamics. Most arrestingly, the improvement isn’t subtle. Redolent of the difference between stock USB and an Audiophilleo-charged USB, a directly connected JKDAC32 is emphatically superior to its USB-cabled self. “Humble pie, Sir?”. Two slices, my good man!

Prospective buyers should consider their system’s current state carefully. You’d slot the JKDAC32 into a system that leant toward sunshine and brightness; its coolness, moisture and slight restraint would be a sound fit. Conversely, the JKDAC Sabre is for rigs that require a kick up the dynamic-derriere or roll-off too early at either end. Single driver divas and valve-fiends might dig it. Broadly speaking, one would find more bass propulsion and dynamism in the JKDAC32.Getting personal: I emphatically prefer the JKDAC32. Despite not being as bombastic as the Sabre version, it’s also not as dry – a trait that creeps into the mix every now and again. The JKDAC32 is the more liquid of the two but also more hooded. It isn’t as warm or as fast as the JKSPDIF + Rega DAC but it’s more tonally colourful and – objectivism be damned – downright more convincing.

More from mainman Kenny: “There are real differences between the JKDAC and JKDAC32. The DAC32 uses a minimum phase filter with low latency. It’s not used in any other DAC chip that I know and what it means is that it sounds closer to the non-oversampling DACs. Which is why the DAC sounds more real. This is not just a difference between one DAC chip and another – it’s between how fundamental parts of the DAC’s function are implemented – in this case the digital filter. There is not much official information about the Sabre DAC but it is said to use a very high speed oversampling filter. The PCM5102 – according to its datasheet – has an option of two filters. I use the low latency, minimum phase filter option. One of the characteristics of this filter is that it has no pre-ringing and therefore no time-smear. I believe this is one of the reasons why non oversampling DACs sound as they do – more realistic! There are other differences between how the two DAC chips go about their job but I believe the above accounts for the main sonic differences between them.”



Some minor niggles. Due to M2Tech’s custom driver (currently required for all JK devices), the iOS and Linux crowd remain out in the cold. Although this will likely change if John Kenny transitions to the imminent MK2 Hiface (which is USB audio class 2.0). The Hiface’s data buffer also causes the soundtrack of video files to run slightly out of sync with the picture. That’s no biggie for those prepared to software correct but it’s frustrating for new comers. Occasionally my JKs would drop their direct-connection to OS X. This is most likely due to a loose connection in one of the two USB widgets, but still annoying. The USB-lassooed JKDAC32 never missed a beat. A shame it doesn’t sound as good.

Concluding. The achievement here is not just a theoretical one: that digital transport quality matters. John Kenny’s DAC twins might come with the compromise of being USB-only but they deliver in spades. The jitter-broom of a Hiface means the tonal-bleaching and high-frequency tension is swept away BEFORE the DAC chip gets its mitts on the one and zeroes. Moreover, this is also one of the most cost-effective ways to acquire the two – USB clocking and decoder silicon – together in one box, iced with off-grid power.

I don’t intend to insult your intelligence (dear reader) with clichés of how the JKDAC32 “competes with units two or three times the price”. Or that it is “recommended”. Or that it is “superb”. Despite superlatives meaning little in a comparative world it is all of these things. No, my wrap is simpler and more direct. The USB inputs on most DACs just aren’t as good as they could be. How do I know? At the risk of sounding like a broken record, introducing a good USB clocker (JKSPDIF/Audiophilleo/Stello etc.) between computer and DAC lifts the latter’s game. Think of the JKDAC32 as a JKSPDIF + DAC chip, a USB DAC whose input is already optimised. In the context of my previously-documented disdain for USB(-only) DACs – that they can’t enjoy the amelioration of the aforementioned devices – John Kenny’s JKDAC32’s impressiveness is re-doubled and redoubtable. Good show.


Associated Equipment

  • MacMini 2010 + JKSPDIF
  • Rega DAC
  • JKDAC (Sabre)
  • Sansui AU-417
  • Audion EL34
  • ProAc Tablette Reference 8
  • Zu Omen standmounts
  • Burson HA-160
  • AKG K-702


Audition Music

  • Caetono Veloso and David Byrne – Live at Carnegie Hall (2012)
  • Pink Floyd – The Wall (2011 Remaster)
  • Lampchop – Mr M (2012)
  • Orbital – Wonky (2012)


Further Information



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Comments
  1. Trevor Robinson

    Your comment relating to USB dropouts when directly connected reminded me of something I had read some time ago when studying the USB interface for data transfer. It is mentioned in an Audio review here too:

    http://www.computeraudiophile.com/content/437-berkeley-audio-design-alpha-usb-review/

    particularly:

    “A cable and its connectors is not a perfect transmission line as it suffers from reflected energy. When a 1.5 meter cable, 3 meters round trip internally, is used this reflected energy is delayed enough to minimize confusion with the original signal at the data receiver. These may be small or insignificant details to some, but are important and critical details for those seeking the highest level audio reproduction.”

    Oftentimes data buses have minimum lengths as well as maximum ones for these timing considerations. Short USB cables may introduce clocking errors and jitter from false clocks via reflected signals that are close enough to the intended ones to cause confusion. Falling over and requiring a reconnect is also a possibility when things get a bit extreme. Odd though that I can’t find much written about cables being too short anymore in the USB spec – perhaps it’s buried in the signal timing diagrams – there are minimum timings (and a period specified as “debounce” alluding to contact bounce in the old days or switching artifacts/echoes nowadays) there.

    All the best!

    • John Darko

      Thanks Trevor. I think John Kenny subsequently ‘fixed’ the drop out issue. I think.