Yep I asked this as well but I have not been able to find any info. My guess is that the service department likely has a schematic that shows it and I'll ask when I take the car in to have the XM installed (and pick up my HFP wheels!!). I would guess it is a 6 channel amp with equal power to each channel. 2 channels bridged for the sub, front channels power the front 6.5's and the tweets, and remaining 2 channels for the rear 6.5in drivers. But that leaves the question of what power is coming from the HU and is it driving anything?