Okay, so I posted this thread a while ago:
http://www.avic411.com/forum/viewtopic. ... celeration
and I thought I had the problem solved. However, when I added a subwoofer to my trunk, the extra power draw from the amp made the alternator noise more audible through the front left speakers (or I started getting picky with the noise). Today, when I installed the I-200 Ipod connector (which works) I grounded both the AVIC ground and what I think is the amp ground to the negative battery terminal directly. The sound is worse now. This is installed in a 2001 Lexus IS300, and it was self installed