I currently have a Harman/Kardon AVR330 and Onix Rocket speakers. At 55 wpc, I'm looking to upgrade the H/K in favor of more power. Since we'll use it for an even split of movies and music, I'd like more of a musical receiver for critical 2-channel audio listening. Budget is tight at about $600, but I have no problem buying used or reburbished gear.
What are my best bets for musical-sounding 7.1 receivers in this range?
My other thought was to hang onto the H/K and get a power amp -- use the H/K as a pre/pro. I'm a little unsure of just how to do this, or which type of amp I should be looking at; a full-blown 7 channel amp, or maybe just a 3 channel amp to drive the mains and center and let the H/K handle the sides, rears and sub. Someone even suggested a pro amp, but I'm not sure how this would differ from a conventional HT amp. Would the H/K really be a pre/pro at this point if it is actually driving 4 of the speakers (plus the sub)?
What are your thoughts for my situation? I know I need to make the final decision, but a little advice from all of you would help to narrow the field a bit.