Many people think that MLs pair well with tubes in general and with the Mac 275 in particular. Other people think that MLs do better with more power, most likely solid state power. I think if you could borrow a solid state muscle amp you could decide which is better for you pretty easily.
My experience with MLs is that I had a pair of Summit Xs and a Pass XA 30.8 driving them. The Pass put out about 90 watts into 8 ohms, so it had some power. I thought the sound was very good but wanted to see what more power could do as the MLs do like power. I bought a D’Agostino Classic Stereo which put out 300 watts into 8 ohms and 1000 watts into 2 ohms, according to Stereophile measurements.
The speakers really came alive with the additional power. They sounded much clearer and cleaner, just all around better. I never did listen to them with tubes, though, so I can’t comment on tubes. I would recommend trying a more powerful amp, though.