the 609 is a great Amp, i bought it last week and I to needed an amp for stereo playback that could handle music. I also figured at my budget all the amps sampled would satisfy me for movies anyway and i only did stereo sampling. I tested the Yamaha 671 and Onkyo 609 at £379 both, and the floorstanding speaker that shined were the KEF Q500s, which blew the QA 2050i, Mission 5s and B&W 685.
I am told the Denon is good and have not sampled it, but the 609 for me was best in stereo by far comared to the 671.
Id strongly suggest demoing them before you buy as they are so different with the speakers of yoru choice.. the extra for the KEF is much advised and since Friday cant stop listening to them....
Good luck with your listening