CD audio from your PC CDRom typically goes over an analog cable to your built-in Soundblaster compatable card. To use a professional audio card, you will need to go digitally from the CDRom through the computer to the audio card. Several programs support this; including Windows Media Player 7 and Winamp (with a plugin). This will take up a stereo pair of outputs while the cd is playing, but will produce higher quality reproduction of the CDs (you'll notice it immediately) because of the higher-quality D/A (digital to analog) converters.

If you have Windows Media Player 7, go to Tools, Options, CD Audio, and turn on Digital Playback. This will route audio cds to whatever audio output is selected in your multimedia properties in the Windows control panel.

If you have Winamp, go to their homepage, search for input plugins, download a CD reader or CDDA plugin, and install it to your winamp\plugins directory. This will also allow you to use EQ and any other audio plugins in real time.

Several other programs do the same job: Music Match Jukebox, Sonic Foundry's Siren, and many other mp3 players.