Ok all, I have a 2005 Audi A8L and it looks like I have a bad Bose Amp.

4E0035223B 4166M

I've done a bunch of research on this and it looks like 4166 is the Bose part number for this amp. It just so happens I found the same part (I believe) for both Porsche and Mercedes as...

Porsche 99764533433
Mercedes 2208273042

The funny thing is the Porsche ones are much less expensive on Ebay and everywhere else and Mercedes a little more and our beloved Audi part is the most expensive. Does anyone know if these other parts are compatible. I can't believe there is anything custom in them for each MFG but you never know.

Thanks!