I searched and found threads regarding the grounding issues with pioneer decks, and i'm assuming I have it.
tweeters make a hum.
disconnected rcas at the amp, hum goes away.
connected ipod through the rca inputs at the amp, no noise.
disconnected rcas behind the head unit, noise goes away.
connected ipod to the rcas behind the headunit, no noise.
I realized it must be the headunit, so I tried to ground the headunit (chassis of deck to a ground source) but it did not help at all.
any other thoughts?