I just recently bought an 06 A4 2.0TQ S-Line and have just started noticing a buzzing noise when I close my driver's side door. I figured it was the speaker but it doesn't sound blown with any type of music at any reasonable volume level. I figured I would see if anyone had any ideas before I took off the door panel or dropped it at the dealership. Oh, and it's not Bose, just the standard Audi Symphony.

 

Is the key turned when you hear this sound?? This is just a shot in the dark, but the lumbar controls in the seats make a "buzzing" sound when you get in and turn the key. I guess they are moving into position or something. Just a guess

 

No, just when I shut the door before putting the key in. I should've clarified the noise earlier. It's more of a mechanical buzz like a vibration off of something, not like something is being turned on. Also it sound like it is in the door or the dash close to the door.