I was in a similar situation. I found an AVA Omega Star 250EX (rebuilt Hafler chassis made from 2004 to 2007) on for $225 shipped. I must say I'm very happy with it. Power for days ( (under) rated 150 watts per@8 Ohms). Drove my 4 Ohms Cerwin Vega VS-150's so hard they were pounding like subwoofers, and scared me. Never heard it clip before actually. It's too powerful for me. Which is awesome! Sounds amazing with a tube preamp (modified Bottlehead Quickie). Bests my rebuilt HH Scott Stereomaster 200 for sound quality with a Scott Nixon Tube DAC. Bought it for a 2nd system. Mainly for rock. And to try the tube Pre/SS amp thing. It's become my main system. Haven't barely touched the Scott since I got the combo working good. My only concern is that, since there's not much info about it. I don't know what to compare it to, if I go to upgrade. I'm afraid that, unless I spend a lot, I won't be happy with the new one I buy. Because of this. I'm thinking Class D next. Maybe an Ice Power, or Hypex amp. Or Class D Audio. I like warm sound though. The AVA isn't incredibly warm, but it's warm.
With your requirements. I would be thinking Yamaha myself. I've seen people say that the only reason they're so cheap. Is because they sold so many of them. And that if they didn't. They would be selling for much more. Very overbuilt. Known for lasting forever. Supposed to have amazing sound quality. The specs are certainly amazing. That's for sure. And most have plenty of power. I've seen very nice ones sell in your price range. There's a lot, and I mean a lot of guys that swear by the Yamaha Natural Sound. I keep thinking I should try one myself actually. But AFAIK. They're more on the neutral side. I think they're a great value though. Either way.
Good luck.
Andy B.