Thanks for posting and good watch. Long rambling post warning, feel free to skip!
I have a MA7900 (big brother to what he has, with Autoformers, 200x2 integrated that has been replaced by the MA8900), and just recently got a MC275. I get the gear at cost, and picked up the MC275 to scratch that itch and knowing while it was not an investment, if I didn't really like it I could sell it and not lose any money.
I'm driving a pair of Sonus Faber Liuto Towers which are rated at 89 dB. sensitivity and 8 ohms. They are not that power hungry (like him, if I am hitting more than a few watts on the meters, it is VERY LOUD, louder than I would normally listen). That said, they can take a TON of power (mainly on movie soundtracks like 'Bladerunner 2049', I actually can get the needles to kiss the 200W mark and the speakers are happy).
Long setup, but where I am going with this is I had no high expectations, or any expectations at all with the MC275. I was pretty sure it would sound good, but not sure in what way or at what cost (tube sound?). Ordered it, got it delivered, set it up. Driving it unbalanced from the MA7900 (no XLR outs).
Wow.
Bass was dramatically cleaner, tighter, and lower. Any trace of bloat was gone, and in its place was texture and nuance. You could argue you 'lost' bass, that is not true, it is what you are supposed to hear!
The highs are what I was not expecting. The cliche tube sound is...warm, muddy, maybe even a little dull. I knew from reviews the MC275 was 'clean', but what I was not expecting was how brilliant, clean, clear the highs would be. I do not mean bright, I loathe bright speakers, I mean the highs just float out of the speakers. The speakers are bigger, wider, deeper, closer. It is magic.
Bonus...the MC275 sounds better at low volume levels, even very low levels. I also built this little kit from Madisound
https://www.madisoundspeakerstore.com/full-range-speaker-kits/fostex-bk-12m-folded-horn-kit-pair/), and these sound great on the tubes, but only OK on the huge SS amp (no surprise). Getting the little Decware in a month and will be fun to play with that on both speakers.
I'm rambling now, but to use a car analogy, the MA7900 is a Porsche Turbo, the MC275 is a Porsche GT3. You lose some power, but unless you are drag racing the GT3 will be more fun. Or if you like American cars, the MA7900 is a Corvette Z06 and the MC275 is a ZR1. The powerful cars generally impress your friends and if you just want to do a speed run, but over months, years, people generally grow to adore the lower-power but more fun cars.