I'd really hate to see you spend the money for a new receiver just to have the same problem. If the receiver is shutting down there must be something connected wrong. My brother has a entry level Denon and drives Infinity Kappa 7's with it. They are 12" 3-way speakers in a sealed box only about 88dB or so sensitivity. Your Klipsch would play about 3 or 4 times as loud with the same power. Are the metal strips in place that go between the binding posts? You said you have two subs, how are they hooked up? Of course, you do have a large room but that would be more of the sub's problem than the Klipsch. Try setting the mains to "small" if not already and see if that helps the receiver.