This review page is supported in part by the sponsors whose ad banners are displayed below

Reviewer: Paul Candy
Financial Interests: click
Digital Source: CEC TL51X transport, Audiomat Tempo 2.6 DAC, HP laptop w/ Intel Core 2 Duo 2.0GHz, 4GB RAM & Windows XP, Clone desktop w/ Intel Core i7 2.80 GHz, 16GB RAM & Windows 7, J. River Media Center 17, M2Tech hiFace USB-S/PDIF interface, Calyx DAC 24/192 w/Calyx Power Supply [in for review], John Kenny JKDAC32 [in for review]
Analog Source: Well-Tempered Lab Amadeus with DPS power supply, Pro-Ject Tube Box SE phono stage, Ortofon Rondo Blue MC cartridge
Amps: Audiomat Opéra Référence integrated.
Speakers: Green Mountain Audio Callisto (on sand-filled Skylan stands), 2 x REL Q108 Mk II subwoofers
Cables: MIT Magnum M1.3 interconnects & speaker cables, MIT Magnum digital cable, Wireworld Equinox 6 interconnects & speaker cables, Sablon Audio Panatela interconnect, Cardas Clear Serial BUSS USB [on loan], Belkin Gold USB, DH Labs D-75 Digital
AC Cables: MIT Magnum AC1, Wireworld Aurora 5² & Silver Electra 5², Sablon Audio Robusto & Gran Corona
Stands: Grand Prix Audio Monaco four-tier rack on Apex footers with silicon nitride bearings
Powerline conditioning: BPT Pure Power Center with Wattgate, Bybee Quantum Purifier and ERS cloth options, Blue Circle BC86 MK5, Blue Circle 6X & 12X AC Filters [in for review]
Sundry accessories: Acoustic Revive RR-77, Auric Illuminator, Audio Magic/Quantum Physics Noise Disruptors, Caig Pro Gold, Echo Busters acoustic room treatments, Isoclean fuses, HiFi Tuning Disc Demagnetizer, Nitty Gritty record cleaning machine, Soundcare Superspikes (on speaker stands), dedicated AC line with CruzeFIRST Audio Maestro outlets
Room size: 11 x 18 x 8’, long wall setup, suspended hardwood floors with large area sisal rug, walls are standard drywall over Fiberglas insulation
Review component retail: €335

If you have an outboard DAC which you would like to connect to your computer via USB yet the DAC doesn’t have a USB input, there are a growing number of inexpensive devices that convert USB to S/PDIF. One of the first to hit the market was M2Tech’s hiFace. I reviewed it two years ago. While it didn’t open up the heavens to shine down golden light from on high, there was nothing that could touch it at $150 especially if you factored in that it could pass up to 24/192 data. Most USB-ready DACs at the time could only handle 24/96 files. Assuming you are happy with your current DAC, why spend thousands to replace it just to gain a USB input? Today there’s a plethora of necessary D/D converters and more spring up almost daily. Everybody is getting in on the act. And most are well under $1,000 [these pages recently covered the April Music Stello U3 and KingRex UD384 - Ed].

While certainly a bargain and able to stream 24/192, the hiFace is hardly perfect. That’s why I use it mostly just for hi-rez music. Any downloaded 16/44 albums get burned to CD-R for playback on my CEC transport simply because they sound better that way. M2Tech obviously realized there was room for improvement, hence their later upscale hiFace Evo. Noting the inherent promise of the stock hiFace, Ireland-based DIYer John Kenny offers his own improved version. A number of readers had emailed me suggesting I try John’s modded JKSPDIF variant. Now in its third iteration, the JKSPDIF MK3 incorporates the fruits of John’s most recent developments and tests. Apart from using the basic core of the hiFace, by now it really has become a unique product in its own right. Example? Kenny uses LiFePO4 batteries instead of USB buss power. Shortly after pitching my review request I received a JKSPDIF MK3 and John's JKDAC32 which I plan to review shortly. John intuited that I’d probably ask for his new DAC at some point so he preemptively killed two birds with one stone. Lucky me! I asked John to describe how he’d arrived at the JKSPDIF MK3 under review today.

I started looking into asynchronous USB-S/PDIF converters after I came across the Musiland 01 device. I'd heard that asynchronous USB was a superior protocol for audio as it uses a local crystal to generate the timing rather than rely on the PC's clock timing. Unfortunately asynchronous USB audio devices then were rather few in number and expensive also. When the Musiland came along, I bought one and liked its sound. This was compared to the sound of the analogue outs from my computers. It sounded cleaner with a lot more detail - see below. I became curious and started to look at the design. 

It did indeed use its own on-board clock as the master timer for the audio play-out, which was great! On the other hand it had only a single oscillator to deal with all the audio stream speeds from 44.1kHz to 192kHz. This means only one frequency will have really low jitter. All other speeds must be derived by some complex processing. There are two speed 'families' in audio, the 44.1kHz family (all its relatives are even multiples: 88.2 kHz, 176.4 kHz) and the 48kHz family (96kHz and 192kHz). For lowest jitter two different clocks are needed, one for each family. I couldn't do anything about that but there were other areas I could address. The power to the clock oscillator was derived from USB and the on-board DAC needed some work.