Don't laugh, Panasonic SA HE200, extremely powerful, extremely musical home theater receiver, about $500 US. (tends to run a bit warm)
Personally, I've given up on Harman Kardon, had problems with my last 2, AVR65 and an AVR520 - I've given up on HK, you're results may differ.
I've had good results with an Onkyo 797, the 600 and 700 may be in your price range. I think the Onkyo receivers I've heard sound very good both for music and HT.
Sony. Don't laugh. I have an STRDB1070 which I love. Don't know what the current corresponding unit is, but this thing is musical (not quite as good as the Onkyo, for music, but very good) and it has SLAM.
Bang for the buck? Panasonic would be my No. 1 pick. Sony No. 2, Onkyo 3. If you raise your budget, things would change pretty quickly.
Good luck. I think a Panasonic - M80 system would be pretty awesome.
One last thing, double check that the receiver you're considering can push a 4 ohm load without shutting down or worse.
