is there a specific model or build date that supports mp3 playback? it seems like there's huge range in price for these changers... i had a 2004 325i when i bought it did not support mp3, (in dash) had advised the service repair guy at Brian Jessel and he swaped it out for one that did support it, looks identical...
i wonder if that's the same with the 6 cd changers, could just be same part# but with a different build date?