The PA-12 is actually a USASpec PA-12BMW DSP ipod adapter. It is connected to the factory stereo via the CD changer wiring in the trunk. Basically it is plugged in place of the CD changer, and the iPod/iPhone plays through this interface. The "Head unit" that you had out of the dash is actually only a control panel (called a MID).

You should do a lot of searching and reading before trying to add an aftermarket stereo to your car. Having DSP makes the task much more difficult. The two general methods are to either replace the DSP amp with an aftermarket unit, or do some custom wiring to "trick" the dsp amp into working.

My question in the first post is about trying a thrid method - using the PA-12 adapter i already have, and and putting a low level signal into that from an aftermarket radio. In my method, the new Head unit would be acting just like an iPod, and the original MID and CD would be relocated to the glovebox - still attached and functioning.

I hope this helps.

__________________

2001 E53 X5 4.4i Sport
Titanium Silver / Black
141k miles, and broken down more than it runs...

2002 E46M3 Convertible with 28k miles - DD