06 CTS w/Bose & Nav:

>50K miles, so out of warranty (plus, Cadillac will want to replace a bunch of parts that likely don't need replacing).

Problem: Intermittent decreased volume (w/ volume control turned up high) and crackling/ buzzing sounds from both the front and rear speakers only on the passenger side. At times it sounds completely normal (even with balance control all the way on the right). It does not appear to be a specific blown speaker, and I was thinking it might be oxidation on one of the connectors on the amp. Any ideas or suggestions?

Thanks in advance.