You didn’t tell us exactly how many rooms/zones you’re talking about, but “multiple” sounds like a lot, and “different music in each one” will require a fairly sophisticated system.
Basically, AVRs are useless for all but the simplest multirooom systems, and there’s no AVR in existence that can handle the kind of multiroom system you’re talking about. And there’s no way it‘s going to happen for a mere $600 – you haven’t even addressed the outboard amplification needed for all those speakers in all those rooms.
I suggest consulting with a specialist like Home Theater Direct.
Regards,
Wayne A. Pflughaupt