I have the USB version and I don't think it's going to make a difference.
The biggest thing is to use the optical out on the unit, I have mine hooked
to an audigy 2 NX, it sounds alright, not great, just alright. This has nothing
to do with Mitch's units, Sirius broadcasts at a low bitrate. If you have a
quality sound system your going to hear the flaws that much more. Make sure your getting a solid signal, and check the com port settings in device manager,
play with those and see if that helps.