thanks for all the advice! seems like the easiest place to start will be with the amp ground under the drivers seat... themore i think about it the more im thinking it shouldnt be the head unit wiring causing the whine, i have the ground wire for it passing through a noise filter, but i didnt think about it grounding itself to the truck via the mounting screws, the exterior casing of the HU is copper, so that would make sense if that helped in the grounding.

biju, how did you get your head unit wired directly to the battery and still work with the ignition?

will update when i get in there and figure it out