DAC quality - Sumiko Pro-Ject vs Headphone DAC/Amp (pico, rsa predator, etc)

I am considering a headphone DAC/AMP combo like the pico or rsa predator. But, I would like to use it about 50% of the time as a USB DAC for my office setup (PC to USB/DAC to Arcam Solo). Any views on whether the DAC in one of these combos is of equal (or better) quality than a reasonably priced dedicated USB DAC such as the Sumiko Pro-Ject.

Thanks