would usb sound better than a sound card

The simplest USB DAC, and a great value is the Benchmark DAC-1 USB. If you want to use your own DAC, then the Off-Ramp Turbo 2 does the same thing.

Steve N.
Empirical Audio
Manufacturer

I use a laptop and USB Turtlebeach Amigo to send toslink to an external PS Audio DAC III. Sounded good, but something wasn't quite right.

I changed to ASIO4ALL and added the asio plugin to winamp and it sounded much better.

Then, I stopped being lazy and plug in the USB cable straight to DAC. WOW! Things just keep getting better.

I have not had a chance to compare against CD as a transport but I have a feeling the PC will come close, but not better (I am using high bit-rate MP3 files). A future project will be using EAC to WAV to USB DAC and compare against a cheap CD transport.

-Henry

If you stay PC (noticed, like me, that you ae thinking of making the switch to a Mac, assuming all is simpler and purer there) I'd give a listen to this:
1)EAC to FLAC (lossless open-code that has a Mac version too)
2)FLAC playback through Foobar 0.8.3 (older version, still sounds best), with the SSRC 24/96 upsampler plugin in Foobar
3) Out to your great PS Audio DAC III (USB doesn't like 24/96, so I'd try coax out w/resampling vs no resampling-with-USB; one choice will be better)

It's what I do (non-USB dac currently), but I'm gonna demo the Wavelength USB Dacs, and Gordon says I should go Mac. My own problem is when i ripped in FLAC I ripped to large album files and use CUE sheets (associated file that has all the tags, etc. and Mac doesn't support that mess). If I go MAc I'll use itunesencoder.exe and batch convert all to Apple Lossless and use iTunes on Mac.

Once you go MAC with a Wavelength DAC...You ain't NEVER goin back. : )

Longtime and Proud Cosecant (V2) owner. Last source I will ever need.

CDP's are dead to me.

Get MAC with PS audio USB DAC if your budget is limited. But if you can afford Wavelength go for it. MAC+WAVELENGHT can't go wrong with this set. Have fun! Enjoy.