Hmm, I'm not sure you can get "good sound with plenty of power" for $500 price range. The "plenty of power" is pretty subjective I guess. My idea of loud and power is pretty wimpy for some of the folks around here! ;\)

Have you thought about used equipment? Perhaps Marantz 7001 or 8001? The former is probably in your price and the latter just a bi more expensive.

I think going with used equipment might give you the best bang for the buck.

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Denon 4520, EPIC80/500/VP180 Speakers