1) First select entertainment via your iDrive controller
2) You should now have an array of options on the top of the screen like radio AM/FM, CD, Aux
3) Choose a radio station you would like to listen to, or track on a CD, or a song on your iPod or other connected device.
4) Once on a station or song you will push the iDrive controller down one.
5) You should have an array appear that says tone
6) select tone and begin to adjust treble, bass, balance.
Let me know if it works for you. I can make a video using iDrive if you would like.