The concert radio in my 99 avant has been having a strange issue where the sound will fluctuate, sometimes it sounds good, then it will become muffled and sound horrible for a few minutes. It does this in both CD mode, and radio mode. Anybody else have this issue? If so, what is the cure?!

 

Sounds like a bad amp. Since this is not a Bose system, you only need replace the head unit.

Bob

 

Bob is most likely correct. But check the wiring and speakers before just replacing the unit. Could be a good time for an upgrade. Be sure and use those niffy wiring adapters rather than cutting up your car's wiring.