I have a problem with the rear left output on our A6 avant, there is nothing at all.
I have tried it with Symphony and an RNS-E and it is the same so not head unit.
In fact when you fade to the rear and left you can still hear the sub going. So I thought I would swap the cables over on the connector going into the amp, this will tell me if it is a connection from the amp to the speaker ot something in the amp/sub that is gone.
So has anyone got a pinout of the sub?