Don't be too quick to discount blowing the speakers themselves though... I managed to go through a few H/K front speakers. It wasn't until the H/K speakers reached revision 3 (according to the orange sticker on the back of the speaker magnet) that they stopped giving out.
...Well, that and I stopped turning up my AUX and main volume to max, listening to a particularly quiet album on my iPod, then forgetting that I did that, and switching to one of my loudest albums that I own!
Anyway, assuming that it's the H/K speakers, I'd recommend just replacing with more H/K's. If I recall correctly, they were about $65 USD each. Not great, but not horrible.