I currently have a kenwood reciever that has 3 pre amp outs, front, rear, and sub. im using the front and rear outs and the new double din reciever i want has a front pre out and a switchable rear/sub preamp out. so my question is how can i run my rear speakers and subs on amps at the same time. would it work to just use the front pre amp for my rear speakers to i can have full subwoofer control at the unit? if my thinking is correct it would just stop me from having front/rear fade option.