I just purchased the X4200 and want to know if/how to use my old Onkyo 805 to add atmos additional speakers? Denon says it came be done but I didn't ask them how exactly. Does anyone know what "port" I use from my Onkyo 805 to the Denon? I'm so new to this it's scary! Also, I couldn't see how to post a new thread in the dedicated Denon X4200 forum?