Well, removed teh rca ground jumper and all my "ground loop" noise is gone. The beeping/buzing/alternator whine is completely gone.
Now there's a base sizzle noise in the system. It's definately induced by the radio as unplugging or muting the line in for the sound card makes it completely dissapear.
I did not that it could be made louder or quiter by handling the black box on th constant 12v in. I had to resoldier the connections in the box when I got it as the wires came completely out (fell out when I turned it over in my hands). I'm going to investigate that next.
I'm beginning to think the build quality on these units isn't so high.........