Originally Posted by funkahdafi
Thanks for the info. What happens if you connect an iPod at this point? Will it just analyze all MP3 files's metadata as well or will the system recognize it as a "real" iPod and use the iPod's own database?
The iPod does not work this way. Although you can (optionally) set up the iPod as a USB Storage Device the music that you can play on the iPod will NEVER appear as files on the storage device and any MP3 files that you copy directly to the iPod as a Storage Device will NOT appear on the iPod and cannot be played via the iPod.
So if you connect your iPod via it's regular USB cable you will not see any songs (unless you've loaded them separately into the USB Storage Device). The BMW adapter cable does not use the USB connection to the iPod. Instead it receives commands via USB and sends them into the iPod via it's serial connection (and receives data back the same way). When it sends a command to play to the iPod, the iPod sends analog audio which goes into the BMW AUX input via the adapter connector.