BAT VK 75SE vs 150SE's or maybe a VK600SE?

A valid comparison would be the 75SE vs. the 600SE, OR the 150SE's vs. 600M SE's, on speakers which do not favor the more powerful SS amps over the lesser powered tube amps. (An inefficient speaker that often dips down to 4 ohms or less would favor the more powerful SS amps especially playing loud rock or orchestral music). Given a level playing field, I would guess that a difference could be heard. You pick your favorite flavor.

Have to agree with Kahuna about the upgrade from 75's to 150's. I went from the 75SE to 150SE's running into Legacy Focus Speakers. Increased power gives more control and of course, more head-room at higher volumes. I think there is always some improvement when going from stereo to monoblocks, however variable. I must say I am intrigued by Dgarretson's idea of using the Zeroimpedance product. May be an improvement even with the 150's, as the speaker and amp are made more compatible.