5th Gen Maxima w/Bose drops rt channel

[flojr]

2002 Maxima GLE with Bose audio has "eq band droppage"! Periodically, the right channel drops what appears to be most of the mid to high end bands. The onset can be concussive, but resets when volume is amped up. I have replaced Bose amp with same and even flipped the front speakers to see if problem followed speaker. It does not. Is there a preAmp or some other component between headunit and rear amp? I have replace HU with Kenwood and Sony, problem persists. It appears to be some issue with a loose connection or bad capacitor, (ground maybe?) somewhere as cranking up volume kicks the sound back into the right channel, where the volume can then be dropped to a more acceptable level. Leaving at high volume does seem to maintain sound, but not always. There is no static or other noise associated with this issue. Just drop out; restore!