'99 540i, no DSP, lotsa aftermarket stuff (amp, MBQuarts, etc).
Alpine CHA-S634 CD/MP3 changer
Alpine KCA-130B Ai-Net/M-Bus adapter
Soundgate ABMW35V4 BMW/Alpine M-Bus adapter
Alpine Changer mounted in the stock bracket:
Soundgate Adapter + KCA-130B cable.
Somewhere in the middle of an MP3 CD....
Yes, it works, and the sound quality is excellent, but navigating the discs will take some patience. For whatever reason the Soundgate adapter causes "lagtime" when pressing the track +/- buttons on the dash or steering wheel, so you can't hit the buttons really fast to go forward/backwards through the MP3s/tracks... In fact, if you push the + button too fast, the track numbers actually start going backwards?!?! But you can still go at a reasonable speed.
If you have >99 MP3 files on a CD, in order to get to #100, you have to go all the way up to #99, then hit + one more time and although the display will say "01" you're actually on 100. Or, you could start at the "real" 01, and hit the - button. In my case, this CD had 146 files on it, so if you hit "-" from track 01, the display says 47 (hope my math is right), and from there you can keep hitting "-" until you get to 01, at which point it wouldn't flip back to 99 unless I held down "-" to get manual seek.
Anyways, the interface is a little quirky and it's easy to get lost, but at least it works.. It's kinda funny in a way.. It's difficult to predict how the Alpine changer numerizes the track numbers based on the directory structure of the MP3 CD.. it's always a surprise what song will come on next :)
have fun,
AK