For what you're thinking of spending maybe trade in and go for a pair of PMC IB2S-As.
Power enough for Led Zep and my
My thoughts were similar reading the original post. Get some good active stand mounts. I had PMC AML1's and they could certainly do justice to any sort of rock. They also shine playing any other sort of music. http://www.6moons.com/audioreviews/pmc/aml1.html
Also to get good loud rock from a small speaker is reasonably possible, but needs lots of power. 15watts is ridiculous, I'm not surprised it didn't satisfy you. You need 50watts minimum.