2008 US 135i professional deck replacement - singal to factory amp?
I'm installing an Alpine 9885 in my 135i.
I've already got an ASWC to retain steering wheel controls, powered antenna adapter and a 9003 harness.
My question is - Does anyone know how the signal gets from the factory deck to the factory amp in the trunk?
From what I read it's over copper, and not MOST bus.
BUT - is it a high level amplified "speaker" (deck) output / (amp) input?
Or is it low level (in which case I'll need to solder RCA pigtails onto the harness I bought)?
Help! This is the only thing holding me back from starting my install.