Audiophile USB to PCM

I had been looking into establishing a PC based music server. Many of the posts on audiogon suggest improvement in performance by replacing the transport with WAV files on PC. Other's note improvement from using USB connections. I have been comparing CD played through Levinson N390S into N32 pre Amp, and Levinson 334 Amp. My speakers are Wilson P7. I have not found the pc Audio to equal my system The Xitel Pro Hi-Fi link connected vis Toslink ton 390s DAC was just fair. The HagUsb is very good. It connects Via RCA digital to my DAC. I found that Flac at its lowest compression was not nearly as good as the best WAV file. Windows Media was not nearly as good as WinAmp set on Direct output. Foobar was closer to the real thing but Less transparent. I do not feel that the HagUSB plays a role in the change in quality In talking too its designer; there are still drivers running in windows that affects the sound. Apparently the new windows platform will reduce some of these issues.

I must say that the sound quality is still very good but not yet equal to the best.

i am also planning on creating a decent PC-based music server for my stereo. now, which way to go? via Stereo-Link Model 1300 USB DAC, or Slim Devices Squeezebox, or should i get the music to my amp through Apogee Mini-DAC (most expensive of the options i mentioned).
which would be best sounding, anyone made comparisons? I don't have a standalone DAC in my system.

How about a SPDIF with a Monarchy DIP? I would like to use a DAC soI just need good SPDIF output.

Has anyone else spent time listening to the U24 as a D/A converter? I have taken USB out of my laptop into the U24 and then ran left and right RCA's out of the U24 into my preamp. This little box has no right sounding as good as it does given how much it cost.

yep. it's qite good :) the only caveat for me is the level, quite quiet in comparison to my cd (the same goes for logitech music anywhere as well btw...)