When you hook up the ipod, are you running it off of the ipod battery or do you have it powered by the cig lighter?
If its the first, its telling you that the head unit is producing noise outside of ground loops, which it is not. If its the later, im amazed
You have a ground loop between your PC and HU. No way around it. Grab a ground loop isolator and test it. If the noise goes away then its 100% a ground loop between the PC and the deck
But then the problem is which is the culpret?
I would yank the deck, connect it to the same power source as the PC and leave the deck right on top of the PC. Hook it up to a speaker and a very small RCA. Check if the noise goes away. Ground the chassis of the deck to the same point, check to see if the noise goes away. If the noise is still there, then we are in trouble.
I'm going to go out on a limb and say that the rampage deck's internals are pretty crappy. They have not isolated the aux in on the deck from chassis gound forcing a ground loop no matter what you do. Your only choice is a new deck or ground loop isolator to make up for the bad design.
Maybe its time to invest ina new deck with a decent design? Any available on the classified forum?