These truly represent almost polar opposites in sound.
The Plinius is a good to very good integrated amplifier. It's on the white/dry side of sound, accurate with good bass, lacking in the hashy upper mid that the Krell has, and more like, much more like the Classé integrated.
The Mac, and I've been to McMasters training, and am a graduate of that austere group...saw it made, analyzed what they're doing.
Mac makes an honest if not a bit misleading product. I DON'T like that they rate their products into 4 ohms insted of 8 like EVERYONE ONE THE PLANET does. This causes universally misleading conclusions. Not hard to imagine.
The Mac is softer, slightly, slightly slower sounding, with a more spongy sounding bass line. The bass has heft, but not as true of a tonality. The bass is rewarded though, with a very quiet background...black and interestly diminsional.
Overall, I'd say, I prefer the Mac, though if they'd only...it's sort of like, "Gee Scarlett Johansenn, please do a tawdry movie, JUST ONCE....we love your bod....
Hope this makes sense and is not offensive.
Larry