Just picked up an old-school a/d/s amp...

[TC535i]

Want to start wiring it to the system.

I can see the output wire colors from the amp to the speakers... but not the input wire colors from the head unit to the amp.

Does anyone know what the labeling for the wires as they come out of the head unit are? I'd like to take them at that level and amplify them, before they get distorted by the stock amp, and run them back into the stock speakers.

[etcetera]

http://www.bmwe34.net/e34main/upgrade/stereo_wiring.htm