I have a dac1 that i just picked up used for $700 (non-usb version).
Since there arent really any usb models on the used market, i coulnt really justify an extra $600 for the usb option, since my $30 soundcard is tested bit-accruate.
I'd love a usb model, hopefully in a few years they are around.
Just got my DAC1 USB in the mail and all setup yesterday. I'm overly pleased with it, huge upgrade from running crap analog outs from my emaigc card. Now I'm running the DAC1 > ARC D120 > Maggie 1.2's. The DAC1 drives the audio research with plenty of power and it ships with attenuator jumpers inside set at -20, so if I needed to bump it up, it wouldn't be a problem.