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Remembering anti-jitter and sundry other small black boxes from the Audio Alchemy days of yore—added to which were upgraded power supplies for an endless game of increasing box count and show me the money—I suffer an instinctive reflex of negativity toward outboard interfaces.

Stick it all in one box, eliminate cables and power supplies. Simple is better. That's my core attitude. Often it's warranted. There's a rationale for the attitude after all. Plenty of experience supports it.

But not always. The U3 demonstrated the exception. From my lot of converters, it made everything with an S/PDIF input sound better.

Red for USB power, green for signal lock
  Be it the Antelope Audio Zodiac Gold with its proprietary 64-bit jitter management and asynchronous 32-bit/384kHz USB input... be it the adaptive 24/96 equivalent of the Burson HA-160D... the adaptive dual PLL solution of the Firewire Weiss DAC2... or the asynchronous 24/192 M2Tech hiFace OEM module which Alex Peychev of APL Hifi installed when he offered to convert my Esoteric UX1 from NWO-3.0GO to most current NWO-M status...

... the $495 U3 was superior in each case. This also factored with the S/PDIF-only Metrum Acoustics NOS Mini DAC Octave. Alternating Zodiac Gold and U3 between it and iMac, the U3 was superior. In fact the U3/Octave combo ruled 'em all. The small monolithic U3 proved to be quite the magic bullet.

Granted, the delta of difference depended—presumably—on how well the other companies had implemented their USB transceivers. Yet not a single one was immune to improvements from the added U3. Perhaps being external and not connected to wall power was an actual bonus? Or in this instance even key? Did it afford superior isolation from the host computer's RF noise and ground contamination? Were Simon's dual clocks more accurate to suppress jitter better? Was the XMOS chip—it also features in Charles Hansen's 24/192-enabled Ayre QB-9—at present simply the premium USB transceiver as Simon believed?

Very revealing ancillaries by way of Nelson Pass' FirstWatt SIT prototype amp with silicon-carbide radar FETs in a single-state single-ended no NFB circuit; Aries Cerat Gladius speakers [on loan] with amorphous-core Raal ribbon, modified Fostex midrange and 12" Acoustic Elegance woofer in a sealed stacked-Ply enclosure with massive outboard xovers

The U3 contributions were easiest apparent on the Burson HA-160D/DA-160 machines. Their earth/wood voicing of powerful bass, rich colors, high density and good flow leaves room for improvements along the metal/air axis of crisper transients, more upper-harmonic energy and more specific micro soundstage cues. In digital, lower jitter/noise seems to most obviously benefit the treble. That's exactly what the U3 did. It injected more light. Spiderwebby stuff of piano decays, bowed string action, venue reflections, wasted air rushes on wood winds and performer auras stepped up and the perception of detail and finesse increased. Space became more audible. Releasing more top-end energy also served cymbals and transient incisiveness in general. It's fair to think of the U3 as a bit of a blood thinner and accelerator like a shot of caffeine. It strips away fine layers of sluggishness and opacity. More detail and dimensionality follow. Articulation refines.

Left, top to bottom: Metrum Acoustic NOS Mini DAC Octave; NWO-M; ModWright LS-100; Bent Audio Tap-X, Esoteric C-03
Right top to bottom: 21" iMac, PureMusic 1.81d5r4, U3, Burson DA-160, Antelope Audio Zodiac Gold/Voltikus, Schiit Lyr

Those who know these machines would have rightly predicted that the Zodiac Gold and Weiss DAC2 with their innately higher amounts of metal and air would have shown a smaller margin of advancement from the U3. I still considered it well worth the fee but it was less than on the Burson twins. For the superlative €700 Metrum converter limited to S/PDIF exclusively, the U3 became the perfect and perfectly priced streaming enabler. That combo surpassed the €3.495 Zodiac Gold/Voltikus on timing rightness, contrast ratio and tone-color intensity whilst in turn shaving off serious functionality (no volume, no headphones, no multiple i/o ports) and being limited to 24/176.4kHz data. Concluding this U3 assessment a few days prior to delivery of the Eximus DP-1, the U3/Octave duo had—by mid August 2011 for those who'll chance upon this article later—become my top reco in the <€5.000 sector selling for $1.500 without USB and S/PDIF cable.

In use, the U3 registered in AudioMidi instantly as XMOS USB Audio 2.0 once connected and properly displayed as well as handled all sampling frequencies from 44.1kHz to 192kHz. Unlike another USB-powered digital device which I'd recently tested, the U3 proved insensitive to actions like simultaneously burning or ripping a disc whilst streaming music for listening. It streamed uninterrupted without losing signal.

Having inadvertently become a U3 convert(er)—and we already know that the U3 is built into the Eximus—I was naturally very curious what the rest of the DP-1's circuitry would bring to the table. For now it was award time for the U3. What more needs to be said when a $495 box can upgrade gear on the level of Antelope Audio's Zodiac Gold or Weiss' DAC2?