Folks;

Car: 2007 Cobalt LT, 2 door Coupe, Competition Yellow, with original head unit (not the Pioneer version). Manual door locks and windows, etc. Nothing fancy.

Backgound: I had the original stock speakers replaced with Polk 6x9's in the back and 6X5's in the front. The installation was done by a now-defunct retailer so, I can't go back to them for help or assistance on the problem.

Problem: Every so often my speakers will go dead for a few seconds and then come back to life with a totally different sound (base, loudness, treble all change). I don't experience any other electrical problems, the lights don't dim...everything else fucntions as it should.

Questions:
A). What could be the cause of this weird problem????
B). What can I do to solve the issue???
C). and, a side question: Does anyone know the specifications for the factory Head Unit on 2007 Cobalts (I have looked everywhere and I can't seem to find any information....).

Thanks for any aid and assistance/advice you can provide!!!!

Joe