Master Clockers & Bros. To exploit the Ref's word-clock feature requires an external master clock from the likes of Antelope, Esoteric, Jay's Audio or SOtM. Not having one on hand, I couldn't test it. One underwhelming prior experience—with an Esoteric in conjunction with one of their one-box players—suggested that, perhaps, home hifi without the need to sync up multiple digital kit via often long cables like studios do might not sufficiently benefit from external clocks. With our Aqua Hifi Formula's RJ45-carried I²S input not being compadre with the Ref's and no Denafrips DAC on hand to instead test the HDMI-ported version, that interesting and potentially superior digital interface was beyond my scope to sample as well. This left me with two applications I could and would test: using this machine as a USB bridge for the iMac; then as SD card/USB stick memory reader.

D300Ref and predecessor D100 Pro

I'd compare iMac/Pure Music --> USB --> D300Ref --> AES/EBU --> Formula; iMac/Pure Music --> USB --> Formula; SD card --> AES/EBU -->Formula. If you wonder why AES/EBU and not coaxial S/PDIF, the former is a 5V format, the latter 0.5V. AES/EBU is the by far more robust signal with the better connectors. In two scenarios, Soundaware's circuitry would process the data before handing them over to the DAC. In the third, the iMac's USB data went straight to DAC. It didn't detour through the D300Ref. For the computer feed, this stripped away any benefits Soundaware's reclocking, noise attenuation and jitter suppression might make. Before we proceed, let's state once more how all of this occurred solely in the digital domain. It involved no changes of digital-to-analog conversion. Any sonic differences were caused by just different transports; and adding or subtracting extra circuitry plus cables. The bits=bits brigade should cry bleeding bollocks by now but that's their religious duty, not ours.

The universal serial bus crosses the bridge to serve me a bill. Past the Aqua converter, the remainder of the hardware was Wyred4Sound's STP-SE2 preamp into a pair of WestminsterLab Unum monos driving Æquo Audio Stilla. Being a very resolving unusually linear full-bandwidth system, if aural hairsplitting was on the books—and I suspected that it would be—I'd have the nuclear particle separator for the job. Whether my ears would be sharp enough was an entirely different question. The USB cable was a red KingRex double-header, the AES/EBU an Allnic Audio ZL 3000.

in USB source mode

As it was, my ears were sufficiently pointy still to make out a clear hierarchy. The best performance came from the SD card. Next best was the iMac running through the D300Ref. Last was the iMac straight to DAC. My first test was the title track from the Dulce Pontes album Lagrimas. This Portuguese fado singer has very powerful pipes. Peaks can become challenges. Moving from iMac-direct to iMac-detoured, Soundaware's circuit removed a certain metallic noise from inside her vocals. Pretty soon the most suggestive term for that was rust. Grain or grit too would be applicable but they lack that grungy dirty-yet-sharp connotation. Without taking her foot off the gas as could be cloned with bandwidth-limited valve amps, the singer's throat no longer was lined with those rusty shards like coarse sandpaper. To a lesser extent, I heard the same in the peculiar glassy timbre of the Portuguese guitar. Defaulting to audiophile lingo, crossing the USB bridge sounded purer. Some form of low-level noise or dirty dither was extinguished. When I finally switched the Ref from USB to SD card mode, what happened was finer and still harder to describe. Sounds felt freer, more radiant and flowering; a bit how ink blots blossom on wet paper but in 3D. This removal of an embedded restraint or rigidity was certainly subtle but nonetheless real and repeatable. WIthout image enlargement—no melon-sized throats or extension-ladder fret boards—sounds off the SD card seemed more alive and a such, energetically not physically bigger. Contrast ratio too went up a click.

Already this early into the Referee game, my prior misses—of identifying an 'audiophile server' replacement for the iMac that made a sufficiently obvious sonic advance to feel worth the cost—had finally flipped into a personally exciting find. Just routing the iMac's signal through the Soundaware was an unmistakable improvement; one which I didn't have to imagine yet which I could enjoy without the brain-numbing ultrasonic pollution of WiFi. This meant keeping what I already had and loved but making it work better. I could continue to enjoy Apple's terrific display and functionality plus get that sonic upgrade which €10'000+ servers with their puny or utterly absentee screens hadn't provided. If I wanted to push even further for special sessions, I simply had to drag'n'drop a quick playlist to SD card. Further potential improvements might still come from native I²S mode and, just maybe, from a more effective external master clock than I'd tried before. In short, this Chinese loaner had found a new home. Time for more tunes.