2004 Roadster with Bose "Sound System Audi concert" radio/CD.  Looking at the radio all displays indicate that it is working fine.  All displays good, not in "SAFE", just no volume at all!.  I do not know if this is related but I have experienced a loud/piercing noise when starting the car in cool-to-cold weather.  No piercing sound this morning when the radio volume quit.  Any ideas?  Doesn't seem possible that all of the speakers could take a crap at the same time.

Thanks for your help.

BC

I figured it out........

What was it?  I'm having a similar problem.  My 2002 Roadster W/Bose has had a definate decrease in the performance of the speakers...  Stereo backlight has been flickering bright and brighter.. now I am loosing all sound when I hit a bump. 

Looked around and found someone with the same problem, but no solution was reported.  (He changed Head Unit, and Amp with no resolution).