My customer's 2008 XKR stereo system is behaving strangely. The sound from the rear speakers about cuts out completely ONLY when she has it set to surround sound mode and is playing the satellite radio. Anyone have a clue what is causing this?

 

The alpine system in my does pretty much the same, I think it's how the Satellite signal is processed by the head unit. In 3ch or stereo mode more sound from rear.

I just move the fader towards the rear to compensate and it helps.