I'm trying to get to grips with what you are trying to do. I have downloaded the manual to see what sort of outputs it has. I notice it has 2 line output sockets, one for the front speakers, the other for the rear speakers. Usually these outputs are 100 - 300 millivolts, although the manual doesn't make it clear, so they need to plug into the high level input to the amp, this are probably maked Radio or Aux.
Have I understood your question?