Hi, I've posted a similar thread in the B6 section, but was suggested I post here too. The rear door speakers and sub are not working in my 2003 A4 Avant, they have never worked since I bought the car and was looking into wether I can test the amplifier to see if it's busted. I was testing it today, the power from the battery is getting to the amp. Strange thing is that I reckoned I could bridge the connector to the amp (after disconnecting it) and let the head unit power the rear speakers without the amp (just for testing sake) but I couldnt get any of the rears or sub to work. I was using the following diagram and bridging the rears, ie 1 to 20 and 2 to 21, but no sound. Any suggestions? Also, any ideas on how to test the amp if it's working? Seems odd to me that the input doesnt seem to work (unless i'm doing it wrong..) BTW, it's all standard RNS D/symphony (not bose) setup.