my passenger side rear door speaker buzzes with the rpm sometimes. I have found that turning the power to the rear controls for the dvd player turns it off. have taken the speaker out. everything seems fine. is there a ground for the speakers that might have came loose. if so where. and i know that possible power wires near speaker wires can cause similar problems. Has anyone else encountered these issues? if so any advice on where to look next. Its really annoying to drive with the buzzing.