I've also got a 2005 X5 with true Digital DSP. I used this to tap into power.
http://www.partsexpress.com/pe/pshow...number=071-580
You simply unplug the fuse for the CD changer and insert the add-a-circuit. Wire the 12V to the wire on the circuit and attach the ground to the bolt above the fuse panel. This way the iceLink will work even when the car is turned off, just as the radio does. Having the DSP module powered all the time is not a problem. This installs at the fuse panel and you run the power cable under the floor over to the area where the amp is. I just completed my install and I don't consider myself that technical when it comes to installing electronics into a car. Still have a slight audio problem that I am working on.

See how much Tom has taught us here!

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2011 550xi Carbon Black/Oyster, M-Sport, Premium Package, Technology Package, Electronic Damper Control, Dynamic Drive, Comfort Access, Active Seats, Surround Cameras

2013 X5 5.0 Space Grey/Black, M-Sport, Premium Package, Technology Package, Comfort Access, Surround Cameras