So, here I am with my new Kenwood receiver and the PA-12 talked about in an alternate thread.

2004 E53 premium sound with DSP.

MID going in the glove box, Cd player going in the glove box or the rear panel with the rest of the audio equipment. I have no adapter to connect to the Kenwood since the stock equipment is staying installed for the time being.

I had a hard time finding the fuse panel in the glove box, it was well hidden.....

I'm going this route now because I don't want to re engineer the audio system. The speakers and amp don't 'need' to be replaced, but a new user interface is necessary.