Best DAC for PC audio direct to amp

Benchmark DAC1 is dynamic with good bass punch and nice clarity. It is good value and has a good reputation for handling jitter with plenty of reviews on it. Sure it is an EBGO DAC (Everybody's Got One) - so no special pride of ownership - but if the sound is all you are worried about then it is a solid choice.

Bel Canto DAC 3!

Get a USB to S/PDIF converter (Trends, Hagtech, etc) then feed to Audio Note DAC to whatever budget suits you. Even their lower level models are incredibly dynamic and musical. May help to have a jitter reduction device before the DAC as they don't reduce jitter internally. I know I've now suggested three boxes instead of the one that you seek but it would be well worth the trouble!

Get the Berkley. Robert Harley of Stereophile says that it performs even better than with a preamp in the system. Plus, it uses a "long-filter" which is similar in performance to Spectral Audio's top-sounding CD player, the SDR-4000 pro. For the money, this piece is a giant-killer!