To add, bothe former and the new HUs do not show BOSE, an the front speakers work directly from the connectors in the brown plug.
AndyMac. Can you help me please. I've slotted a concert II into my 2000 A6, and expecting a CAN-BUS that I bought on ebay from Germany. One problem bothers me though. When I turn the HU on, sometime the front speakers don't work, only the rears, but if I push the power knob in and out a couple of times, it usually cuts in. I chcked the brown plag - it is not a contact problem there. I also found several other people on net having the same problem. Any clue why this would happen and what the fix for it?