Jason; This sounds a lot like the problem I had with my install.
I moved the ground leads all over the car and could not get rid of all the noise. This was with an Alpine 4 channel amp. I finnaly gave up on the Alpine and went with a Kenwood that had floating ground inputs which got rid of all my noise.
You might want to see if the A/D/S line has a unit with floating grounds or move to a brand that does.