If its between those 2 then definitely the 640. I would demo the rotel RA04 too but for me a remote is absolutely essential.No remote would be as bad as having only 1 speaker, but if you can live with it then i would give it a demo. I have also not found any unbalanced output problems with mine, but then i would have to be sure what that meant first to actually tell! Seriously though, mine sounds great with no balance issues.