The previous install was a total pain due to the limited room behind the chassis...wonder if all Bimmers suffer from this?
Anyway, I learned a bit from all of that, and sorted out wiring a bit differently this time.
The six RCA outs require a lot of real estate, and wire routing is critical. Tried to ensure that the wiring isn't too stressed, as I believe I had a lost channel the last time due to kinked wiring.
I'm not using any of the speaker-level wires, so I went ahead and clipped them off...so that's eight wires that don't need to clutter the wire harness.
I wrapped the harness in electrical tape, and the bumps are where the wire ties reside. Metra connector at the end of the wire harness is a direct fit to the factory BMW connector.