Sorry to hijack this thread.

But for a solution to Audio Streaming to the 2006 BMW X5, you can soldier in a A2DP Bluetooth 3.0 module, inside the BM53 radio module.
The radio module then powers the BT unit and audio out of the BT unit can be tapped into the Aux Input.

You then have 2 seperate BT receivers in the vehicle, the OEM one for Handsfree and the A2DP one for Music streaming.
I single phone can be paired to both units at the same time, you just uncheck "handsfree" when you pair the unit in the BM53 enclosure.

Sorry, not sure if this has been mentioned before.
I just found it to be the best and most simple solution that keeps everything OEM, no holes, no cables, just Plug and Play once you have installed the BT unit in the BM53.

EDITED: Changed the year of Vehicle.