Have owned my Preludes for quite along time and absolutely love them.
I've driven my MTS' with my old Phase Linear gear, Sim Audio, Legacy-Audio, Sunfire and Krell.
Personally, I've liked them all!
The only difference, in preference, was when I drove the MTS' with the speaker outputs on the Krell vs the speaker outputs on the other amps.
I prefer the Prelude's subs driven by the preamp and the towers driven with the amp.
I've not driven my Preludes with anything other than higher output amps so can't comment on how they would sound with tubes.
The only thing I would say regarding the Preludes is one can never have too much quality power.
How do you like your Preludes?