Does anyone know anything about replacing the reciever from the premium 7 speaker system in the EX with an aftermarket one. I'm mainly concerned about the factory sub and how it is powered. Does the factory radio amp power the sub or is it powered by a seperate amp? Same goes for the rest of the speakers. It wouldn't be much fun to fry the amp in my aftermarket reciever if it can't handle the load of the sub and speakers.