music reference rm 200 mk ii versus mcintosh 275 v

my speakers are thiels cs 6. i listen at low to moderate
sound levels.
I have run an older RM200 with my Wilson WP7s in a 1600 cu. ft. room very effectively for several years. Given that these speakers present challenges to an amplifier that I am guessing are similar to your own, I can tentatively recommend that you try it. I have had no experience with the Mac, so cannot offer a comparison.