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There was a consistent difference. The 'detour' through the U2—involving an extra cable by way of the i2 Digital X60—had the sharper honed transients which was particular apparent in the bass. It also had the more violent dynamics. On demanding fare like close-mike'd Concha Buika with muted trumpet and played back at high volumes [Niña del Fuego, "Volver Volver"], things were more startling and hair-raising but also closer to the edge. On thickly textured recordings like recent CD flame 21 Strings [Al-Andalus Ensemble], the greater transient acuity of the U2 separated better, its dynamic acceleration made Tarik Banzi's soaring oud improvisations more piquant and virile, tone fuller and fleshier.


I'd assumed that if any differences were audible, the detour would create an overall softening by injecting a small fuzz or blur into things - the additional pane of glass in the usual analogy. Not. Exactly the opposite. Assumptions duly slain, one might speculate. It must be the hard physical separation/isolation of the computer interface—where audio circuit meets PC circuit so to speak—that's responsible. The U2 packs it in a discrete aluminum enclosure. It shares not the PCB with the D/A processing nor does it hover in very close proximity inside the same casing. Is that why it's superior?


Feeling a bit flummoxed because audiophile wisdom of simple is better seemed capsized, I suddenly remembered my earlier interview with April Music's Simon Lee: "I am listening to PC with normally ripped CD 44.1 to WAV played by Foobar upsampled to 24/96 over the Stello U2 into our DA100 Signature DAC to be upsampled to 192kHz. From there I go into the new Ai500 and MG20.1 speakers. This is fantastic! You can even compare it with dCS. You will see very soon. We are optimistic about PC or streaming media playback but we have to see what SONY/BMG, Warner etc will do for HQ music. For the time being, we will concentrate on standard CD playback (CD or ripped) at 24/96 played via 192kHz upsampling."

Readers not familiar with the Stello DA100 Signature converter must know that it—like the Ai500 above—sports its own USB input. Yet the designer listens via the U2. Now I can appreciate why. I simply don't understand what makes it so. But my ears tell me that Mr. Lee is correct. For music lovers blissfully ignorant about engineering matters, that's good enough.

It doesn't remove the extreme niche stigma. Anyone buying his/her first outboard DAC today will surely choose one that has its own USB input already (just like the Ai500 below and that's not even a source component). Ditto for any new one-box player. Think Esoteric's fabulous SA-50. The U2 thus isn't a forward-looking product so much as it is a retroactive solution. It honors existing RedBook legacy investments. It's a retrofit upgrade to stay current, no soldering required, no original warranty voided, no extra power cord or AC outlet or rack shelf necessary. It gives old-fashioned two-channel audiophiles who are stiff with reluctance to embrace PC audio a simple and cheap solution to test the waters. The great surprise is how the U2 can better existing built-in 'integrated' USB solutions.


Does U2 stand for you too - as in, can finally catch up with the streaming generation? You bet. Color me surprised but convinced. Cheers to Simon Lee and compadres for keeping it cheap.

April Music website