I’ll just add to what Tom already mentioned above. Odd vs even order harmonics of tubes upon clipping, the later being much more “palatable” for the ears
Clipping is typically not an issue with the McIntosh Amps of either variety?
Damping factor between solid state and tube amps is often the biggest source of difference in the perceived power. What is technically a better control over the woofers with a solid state amp, vs a tube amp may be perceived as dry, less analog or powerful bass.
The “looser”, “fatter”, “rounder” more “analog” and often “tuneful” bass can be perceived as the more powerful watts of the tube amp.