Hey guys, I am having some serious audio problems.. First, here is some background on my setup. Ive got a 2004 matrix XRS with the screen in the dash. Im using a MicroATX case under the passenger seat. Right now its being powered by the inverter in the dash (not the cause of the problems) until my DC-DC PSU comes. Ive got WIFI and GPS in the dash, a 250 gig HD, Sirius, and am using the external Creative MP3+ hooked to my amp for sound. (See pics at bottom of post).

I have a horrible alternator whine when my sound card is connected. I have my case grounded to the same spot as my amp, and am using 8 AWG wire. Even if the computer is off, I still get a whine. If I disconnect the USB cable from the sound card, the whine stops. But if I even touch the cable to the metal around the connector, it comes back. Any idea on what could cause this?