98' A4. My Cd player Freezes so I assume it's half knackered but I also suffer the rear speakers dropping out and the fronts then loose the base or for some reason just sound "tinny" Also when you turn off the Concern (non Bose) head unit when this happens and back on all is fine for 5 seconds before the rears cut out again. You have to turn the engine off before the sound is restored. This has happened to me 3 times in the last 2 days. Prior to that a few times a week Currently Im booked into a Audio centre on Friday so they can have a look. .. sooooo DO I put up with the CD changer errors and just hope they fix the general sound issues. Or Do I change the head unit for something that accepts MP3 cd's and get the garage to check the wiring and rear amp over for problems and hope they fix it?