Should I be considering a separate amp to drive just the front mains (two pair of Advents wired in parallel=4 ohms)? I've had no trouble running a 5.1 HT with a cheap Sherwood. I upgraded to the Denon, which ran the Advents fine by themselves, but when I hooked up the rest of the 7.1 surround system, it blew. On its way back to Denon for repair, but I'm thinking it can't handle the mix of 4 and 8 ohm speakers and that I need a separate amp for the fronts.