Question about hooking AVR up to Power amplifier

Never have done this before. My TX-SR805 blew it's front left channel, and will cost $250 to repair so I'm not going to do it. I am going to connect a 100W x 2 Harman Kardon amplifer to the two main channels and use it as a pre-pro. I presume I can do that correct? And then use the remaining 5 channels (center, and 4 surrounds) through the Onkyo receiver?