Hi Hugh. Very interesting choices. I really am looking forward to watching how this progresses for you, and what you choose to do.
My personal experience?
- When you are this level (which you would not be if you did not care about EVERYTHING)...then the idea that something 'wont make a difference' kind of falls to the wayside in my experience. Does anybody 'need' the Boulder 3050 monos (1100 watts/channel into 8ohms and 1500 into 4... doubling both figures at peak) to drive a pair of 93.5db efficient XLFs? No...but do you hear a difference? I feel absolutely certain you do.
So coming to your situation,
- if you love the Mephisto best (I certainly preferred it to Antileon and Colosseum by a good margin), then I find it difficult to believe you would not hear the difference with either of the speakers
- What is the best combination? Pass...I dont know the latest gen of Evos. I do think the Mephistos are magnificent
As for stereo vs mono on the semi-active Tridents...I suppose the stereo vs the monos 'might' NOT be that different on the Tridents, but I would probably guess its more 'it does not matter 'that much' rather than the sound signatures are truly indistinguishable and identical at all levels in all rooms and with all music. Personally, I would say that here, there might be a little argument for going stereo vs mono...as opposed to whether you would hear the difference between Mephisto vs Evo on either speaker.
I will let you know when we've heard the XVXs.