John Kenny JKSPDIF MK2 (modded m2tech Hiface) review


Often the benefits of even the most luxurious (read: expensive) audio upgrades are tough to pick. They seep into the listener’s consciousness over a number of weeks – an additional lilt there, a touch more decay there (and that’s even before we factor in product burn-in). On the other hand, some things are just cut and dried superior, night and day better, over and done deal. And so it is the case the with John Kenny’s hot-rodded, battery-modded M2Tech Hiface.

Six months ago, when quizzed about the stock Hiface, you would have gleaned an indifferent opinion from this audiophile. A number of folk had talked up M2Tech’s magic-bringing prowess. Was this a case of Italian braggadocio? My response was cool. I fed it into a Bel Canto DAC 3…and then an MHDT Paradisea. Nup. Nuthin’. Meh. Moreover, its presentation was muddled, confused, uncertain. Or maybe I was confused. Either way, I just wasn’t hearing it. And if I don’t hear it, I don’t hear it. And if I don’t hear it, I call it as such.

Conversely, Taiwanese-based Firestone Audio brought jitter rejection that I could hear first hand (no question) with their Bravo re-clocking unit. It was more precise with instrument locations and slightly less fenced in. It also lifted micro-dynamics a smidgen. The caveat being that it was markedly less effective with more exotic devices.

The idea behind the original Hiface was to reduce jitter. Now on its second revision, Kenny has taken on EMI/RFI reduction too. MK2 modifications move things a stage further by preventing the USB power supply from poisoning the digital soup. This sees the Hiface COMPLETELY isolated from the computer’s (5V USB) power feed. How much? The MK2 heads out the door for 270 Euros (AU$350). Only a hundred or so bucks more than the standard Hiface’s Australian sticker price.

John Kenny: what’s-a-matta-you-hey? gotta-no-respect? Those Italians at M2Tech didn’t do it for you either?

“I initially started to look into these asynchronous USB-SPDIF converters when I became aware of the Musiland 01 device. Asynchronous USB was known to be a superior communication method for audio as it didn’t rely on the PC’s jittery clock for its sensitive timing. Unfortunately, asynchronous USB audio devices were expensive until the Musiland came out. I bought one, liked its sound and started to look at the design.”

“Yes, it used it’s own on-board clock as the master timer for the USB communication = asynchronous USB, great! On the other hand, it used a single oscillator to deal with all the audio stream speeds from 44.1KHz to 192KHz. This is not a good idea as it means this single clock has to go through a more complex process to derive these audio clocks. There are two speed families in audio, the 44.1Khz family (& all it’s multipliers 88.2KHz, 176.4KHz) & the 48KHz family (96KHz, 192KHz). It is best for lowest jitter that a different clock is dedicated to each family. I couldn’t do anything about this but there were other areas I could address. The PS was derived from USB power and the on-board DAC needed some work. After having completed my modifications I was pleased with the sound.”

After some success in modding the Musiland MD01, Ireland-based Kenny turned his attention to the Hiface: “I got a Hiface & in stock form it sounded nearly as good as my modified Musiland…(it) had two oscillators, check. But now my focus was on the PS. This was derived from the USB power. I put a scope on it to see what noise there was & saw a distinct spike. At the same time I had some ideas about using a new type of battery that was designed for electric vehicles – an A123 LiFePO4 battery. This had phenomenal specifications & it’s 3.3V output was just right for powering these digital circuits. I bought some. I analysed the Hiface circuit & realised I could isolate the power to the clocks & power them from a battery. The change in sound was phenomenal & the scope proved it also. I also used a battery for other areas I considered critical. I documented all this work in the public domain on a DIY audio forum. Some people tried the modifications themselves and reported the same findings – a huge increase in the quality of the sonics. Enough people contacted me to do this micro-surgery on the SMD components on the Hiface board that I started to do this as a service and eventually evolved it into a more user-friendly boxed component – the MK1 Hiface.”

“The move to a MK2 was precipitated by the fact that the MK1 still had some improvements that could be applied to it:

– it still used the 5V power from USB to power some parts of the board. This was addressed by some users by cutting into the USB cable & tapping a 5V supply into it – effectively dispensing with the USB 5V supply

– it still needed an external battery charger for these LiFePO4 batteries. These chargers are not yet very common.”

“So the MK2 addressed both of these areas and included a 5V supply and LiFePO4 battery charger inside the box. There were some other changes also made. All this proved to be effective in incrementally improving the sonics again and in making the MK2 immune to the quality of the PC’s power supply and the quality of the USB cable used. It also made it a more user-friendly, usable device.”

John Kenny’s modifications retain the original Hiface’s 24/192 asynchronous data handling – it’s still bit perfect – and it still leeches digital audio from computer via USB. The MK2 box swallows the original Hiface whole – a black box with a switch and a blue LED; BYO power supply. Kenny admits that a switching PSU will probably work but it won’t provide the best end result. He put his money where is mouth is and had a “proper” (with power transformer inside) 12V AC/DC power supply shipped to my door. My sample unit offered BNC connectivity, but RCA is also available. Kenny also has one foot in the future with I2S options, but that falls beyond the scope of this review.

A copy and paste from Kenny’s website explains how it all goes down: “The device draws no power from the USB connection. This has again improved the sound! A 9V to 12V DC supply is plugged into the 2.1mm socket. When the unit switched on this acts as the power source for the 5V & 3.3V internal regs. When the unit is switched off, it powers the internal battery charger. Charging takes place until the battery is again full & the charger turns off. Without any charge the battery will last days. This is a plug & forget arrangement.”

Kenny was aware of my lack of results from the stock Hiface. I think this made him a little nervous. If I didn’t hear it, I was prepared to call the emperor naked. Ultimately, Mr Kenny had no need to worry…
My listening sessions began with one of two budget systems I’d been playing with recently: a Redgum Sonofa’GUM 5500 into Usher S-520s. A tremendously resolving pairing with oodles of resolution at both frequency extremes. The midrange can’t cut it with the big boys but it is decent enough. DACs to hand: a Red Wine Audio Isabellina, an Eastern Electric Minimax and my daily listen, a TeraDak Chameleon.

The test system’s rear end counterbalanced the politeness of the Isabellina just so. Bass notes from Bjork’s intense “Hunter” were already low slung and weighty. Enter the modded Hiface (connected to a MacBook) as transport. Everything went widescreen. Wider for sure. And taller. I was anticipating a little difference, but not this much difference. There was something going on. Something great. Tighter, better extended bass and a more analogue treble – duly noted. Moreover, the Isabellina was less inhibited when called upon to rock out (its shyness with inferior transports not an issue here).

Switching over to the Eastern Electric MiniMax and the differences between the stock standard USB (using an MHDT Labs cable) and the battery-fuelled black box remained stark, but not quite as dramatic as with the Isabellina. Perhaps the jitter rejection is more effectively implemented on the MiniMax? Music without Kenny-Hiface brokerage was dead from the neck down, dull, lifeless. It sucks to be plain-Jane USB with such a marked contrast in soundstaging. Conclusions irrefutable? Yes, to be sure, to be sure.

Another day, another test system: a DIY SET from Eric McChanson feeding a shabby pair of Fostex 126EN monitors. The midrange detail from this duo is something to behold. It is Sherlock Holmes-like in unmasking the ‘truth’ of sound. Bjork’s “Hunter” got another pounding. There it was again: wider, taller. There is an insistent, metallic percussive ratatat that emerges from – and then pounds – the right channel for the first minute of “Hunter”. It’s both irritating and necessary. The modded Hiface brought superior definition to the shape of this synthesis, making it easier to visualise the sound’s shape in three dimensions. This lift in performance transcended phrases such as “better resolution” or “more detailed”. The reproduction was more organic. Think farmers’ market on a Sunday morning, home cooking in the evening.

Let’s change DACs again. The already “earthy” TeraDak Chameleon proved unable to resist the charms of the Hiface, but the results were the least pronounced of the DAC gaggle. Could I live without the Hiface with this DAC and stick with vanilla USB from my MacBook Pro? Nope. No way. A/Bing a 24/96 FLAC of Talking Heads’ “Cities” sealed the deal. John Kenny’s mods unearth degrees of vibrancy and vitality in the complex-but-buoyant mix that render the USB feed as ‘soapy’.

Someone else needed to hear this. The M2Tech Hiface had been transformed into something quite special (to my ears) and I wanted third party verification.

My good (audiophile) buddy Andreas Von Stenhausen is bit of a digital audio veteran. He has a lovely dedicated listening room: 4.5m (W) x 5.5m (L) x3 m (H), rugged-out wooden floors – a very relaxing space – in which a pair of Rogers LS4a are powered by the KT88 behemoth that is the Jadis Orchestra Reference. The system’s flavour is one of abstemious class. DACs of the day were the Eastern Electric MiniMax and a two-box (TeraDak) Valabs (one notch down from the Chameleon) – in short, a Sabre-chipped DAC and a 8 x TDA1543 NOS DAC. There’s little need elucidate with the customary ifs and maybes. The standard USB on both the Valab and the MiniMax were far, far inferior to the breadth and immersive nature of John Kenny’s box. Andreas preferred the smoother, less-excitable nature of his Valab and I can see why. The battery Hiface brought out the best from within.

Most audiophiles admit that digital sources can sound too edgy, too dry. A very cheap tweak of which I was formerly unaware, clipping an RF attenuator to the digital cable schmoozes the ones and zeroes into a neater line and with it came wetness to the strident string and horn sections of the Michael Nyman band. However, the use of an RF attenuator took the NOS smoothness of Valabs all the way to uniformity – too bland. The MiniMax better benefitted from the emotional grounding of the attenuator.

Bjork’s flamenco flirtation of “So Broken” is as far away from her “beats and strings” obsession (that bore Homogenic) as one can get. The elasticity of guitar strings were unmistakably more real, more tangible, more THERE with the Kenny-Hiface than without. The mortuary slab of unhindered USB was all too evident, Kenny’s device rendered essential. Again.

Andreas had been raving about his Auraliti PK100 filer player for some weeks. The inevitable showdown was short and sweet, our collective conclusions clear cut: there was little to separate the Battery-modded Hiface and the Linux-powered Auraliti. Soundstaging was similar, both connoted similar tonal density and spaciousness. However, some slight differences between DACs should be noted here: the Auraliti into the MiniMax was a tad more ragged at the edges than with the Hiface/MacBook/AyreWave trio. Some line attenuation helped. Auraliti into the Valabs was just right. Likewise Hiface/MacBook into the Valabs. Third-party verification complete. Box ticked.

Need more context? My trusty Firestone Audio Bravo re-clocking unit is a neat and tidy way to chip away at jitter. It requires no special drivers and will accept inputs from both S/PDIF and USB – it’s more flexible than the Hiface. However, flexibility be damned, John Kenny has done enough with his mods to ensure the Bravo’s glory days are behind it for those that push ones and zeroes with iTunes, Foobar and the like. The Bravo only bridges half of the chasm between standard USB and Kenny’s total isolation from the USB power supply.

The improvements from some affordable hifi upgrades are so obvious, so plain that it is easy to explain them as such. John Kenny’s second round in the ring with modifying the M2Tech Hiface is one such product. If you’re a dedicated computer audiophile – with either a Windows PC or a Mac as transport – you NEED this device. Live with it for only a few hours and it renders the standard USB output as dead from the neck down. As evidenced by my own experimenting with a variety of DACs, your mileage will indeed vary, but I struggled to find a DAC that didn’t justify the asking price. I thought about tagging this battery-powered Hiface as “highly recommended” but it’s better than that – instead, I have to go with “essential”. Got computer? Get this.


Associated Equipment

  • MacBook Pro
  • Auraliti PK100
  • Firestone Audio Bravo
  • Redgum Sonofa’GUM 5500
  • Eric McChanson DIY SET
  • Usher S-520
  • Fostex 126EN monitors

Audition Music

  • Talking Heads – Stop Making Sense (1983)
  • Bjork – Homogenic (1997)
  • Miles Davis – Sketches Of Spain (1960)
  • The Essential Michael Nyman Band (1993)

Further Information

Written by John H. Darko

John lives in the NOW + HERE = NOWHERE. He derives an income from the ad revenues of DAR. John is also an occasional staff writer for Stereophile, 6moons and TONEAudio.

Twitter: DarkoAudio
Instagram: DarkoAudio
Facebook: DAR


Leave a Reply
  1. The only real “problem” with the hiface is that its “cheapness” sticks in the “craw” of people who want to spend stupid money on digital audiophile products.I have no problem with people spending big money on analogue products because you will usually get some engineering value from doing so but I feel this digital stuff is a big con, lots of money for half empty small/slim) boxes etc, and half of that (emptiness)is the PSU.

    If the Hiface sounded sounded poor that can only be because the digits are being modified or corrupted on their way to the DAC, the hiface has no “sound” as far as I can tell, its only job is to convert USB type data to PCM and then precisely clock the PCM data to the receiving DAC from a USB port,the DAC then has a more precisely timed signal to decipher and recreate to an analogue signal, this I can appreciate will and does benefit sound quality from what I have heard.

    These good folks bring ordinary people a very low jitter device with precision clocks to relieve us all of the Hi-Fi industry’s “hierarchy” and by that I mean their reluctance to manufacture a device for less than a gazillion dollars before they will add a stable TCXO clock/precise crystals etc or anything “useful” to genuinely assist sound quality.

    It’s a reoccurring underlying theme/sneer in all the Hiface reviews I’ve read from HiFi reviewers…its just too cheap, how can something that cheap be any good? what we need is something more expensive and based on HiFi voodoo than no one can understand.

    • I’ve heard the normal Hiface and the John Kenny modded version. The latter is a good few strides better than the former to my ears.

    • “I feel this digital stuff is a big con, lots of money for half empty small/slim) boxes etc, and half of that (emptiness)is the PSU. ”
      I think this statement is not accurate for all digital products, assuming you include DACs as one of the digital products doing the con act. If you are not, then apologies from my side.

      I think that other than the clock, the analog stage is the most important part of a quality DAC. Remember it is this analog stage which is the starting point of the analog audio signal which ultimately comes out of the speakers and it is vital that the signal integrity is preserved with as much fidelity as possible.
      A good analog stage needs a robust power supply which will never be current starved. And design and manufacture of quality power supplies is not cheap. I for one do not trust those cheap wall warts or USB powered dacs which will never have the filtering, regulation and current delivery capabilities that a quality power supply can provide to the analog stage.