Good work jeremyp ...
Glad to hear that you overcome the problems with PDC tomes, volume and remote on/off signal, cause I think I will be the second one who's gonna try it.
There was another member here who did the same thing but with a NON pnp amplifier. Here's the link (post #12):
http://e89.zpost.com/forums/showthread.php?t=280841
I asked him a lot of questions and he really gave a lot of info. Take a look at the attached file and pay attention to question number 7. He says that
there's indeed a small gauge black cable for the acc on/off signal, which is common to all BMW's and you can't miss it.
Why didn't U use that cable to feed the acc on/off signal to the amp ?
I think you should give it a try and let us know.