I am adding an amp to my system. I bought an inverter or diverter whatever they are called. The kind I bought you tie into your rear speaker wires behind the head unit which then converts to RCA's. Is this possible with the factory system. If so, is there a schematic which tells me which wires on the plugs are the rear speaker wires. The info I have got on the remote wire is telling me to run it to the fuse box. Please help, Thanks