DSP version? tell us more

I ran a non dsp one in my e46 adn when I moved to the e53 with DSP, I bought the DSP version. great and simple product. very reliable and easy to install.
Amazon.com: USASPEC PA12-BMW-DSP iPod In-Vehicle Interface Adapter for BMW DSP Style Radios: Car Electronics

http://usaspec.com/userfiles/editor/...L_20100622.pdf
again, its a great product

this is an iPod/iPhone interface, which is far more complicated product than the simple AUX... The OP was looking to activate his AUX input on the radio, which is an additional input into the system, while the USAspec product is taking over the CD changer input thus eliminating the CD changer from the system...

The AUX can be build from simple components for under $5... the iPod/iPhone adapter can be build from components for about $40-80, depending on the type of microcontroller used...

the ipod adapter is a good product indeed