I have an Infinity 7520a two channel amp that is not being used. I plan on upgrading the door speakers to 6.5s in the future and adding the rear speaker kit. Is it possible to power the doors with the Infinity amp and the fronts and rears with the stock hifi amp? I thought I read on here that the stock amp has built in crossovers, so it might not be possible to power the PNP rear kit with it. Any thoughts? Here are the specs for the amp:
http://www.crutchfield.com/S-YZOv5osdgx5/cgi-bin/ProdView.asp?g=120&tab=features_and_specs&i=108R7520A#Tab