Yes, I agree, it has got to be a bad ground somewhere. also, where did you run your RCA's are they with the power wire? because I have been told by Rockfords Audio Tech's that you should not run the power wire in the same area as the rca's (they "backfeed" sort of thing) so run your power wire on one side of the car, and your RCA's and Remote wire on the other side.
For the lack of sound from your sub, If I read right, it is a DVC? how do you have it wired?