Use one of the several USB DACs out there and avoid using the sound card altogether. This gets the critical circuitry out of the RF hell inside the computer case. I've thought about putting together a hybrid solution where the USB DAC sits on your equipment rack connected to the preamp. If your music is on a laptop, you just plug in the USB on the laptop when you want to listen to music. You have the laptop to use for normal computer tasks AND you have your music collection with you when you're away from your main system.
Dick
Dick