I just had the dash unit for my sound system (Bose) replaced under warranty in my 2001 A6. There was odd behavior - occasionally stations would change on their own and the CD player would skip tracks. The replacement unit is identical to the original, but the sound is overwhelmingly bass heavy. Adjusting the controls can make it better, but not as good as it sounded before. I called the dealer than installed it and they said the bass was controlled by the amp, not the dash unit.

I'm wondering if this is true. Are there any trim pots for adjusting the sound on the back of the unit? Any hidden codes to control the subwoofer? Or did I get a bad unit?

 

sounds like you got a bad unit unfortunately....

there are no controls on the amplifier if i'm not mistaken. I have a 01 A6 too and I always adjust the bass properities on the head unit.