See also:

USB audio interface/audio interface for mobile phone
OverviewIt is possible to connect external audio devices. They can be operated via iDrive. Sound is output over the vehicle speakers. Options for connecting external devices > Connection via US ...

Screw thread
Push out the cover by pressing on the top edge. ...

Tone
Only treble and bass can be set in the rear for headphones. The settings are made separately for the left and right headphones. Operation is the same as for the front tone. ...