Well im trying to hook up a sub and amp to my factory headunit. I have a 2004 A4 with the non bose stereo. Whoever owned the car before me had an aftermarket stereo because I can see where wires have been spliced in the doors and on the amp, and some holes were an amp was probably placed. Anyways I have everything hooked up, except I cant get the line output converter to work. I have it tapped directly at the amp. I noticed before I even did the installation that the rear speakers didnt work. so i popped off the shell and saw there were speakers there. once I hooked everything up and didnt get sound i popped the shells off again, and noticed that there wasnt a component at the top behind the grill and it looked as though there should have been and there is an extra wire that seems to go to a component on both doors. I jut thought that a4's without the bose have comp. in the front and just 5 1/4's in the rear. I have a sub on the rear deck to which is run off the fact. amp and the only thing that works. I took the door speakers iside and tried to hook them up to a radio and there is no sound. im guessing they are just garbage. I know all this is kinda hard to get but mainly im asking if the rears are components. I have an ultrasport if that means anything to.
Derek

 

Not sure about the B6, but on the B5 non bose, there is a small amplifier that is attached to the driver's side rear speaker that powers the rear units.