A Crown XLS amp is a cost effective way to add a bunch of power to see if that's the issue in any case, the XLS1502 would be what I'd aim at (I own several XLS1500s, the gen 1 version of the same amp minus some extra features in gen 2). Still, it's only about a 3-4 dB advantage over your avr's amps. No particular need to use same company's electronics altho if you're Canadian and trying to support companies in Canada that's understandable somewhat. Anthem makes some nice power amps, tho I wouldn't bother with their avrs much.
That would all depend on which particular amp, you can't judge solely by class at all. Some of the best amps are class D and there are poor performing AB amps as well....
