Hey Soloist,
I used to try to run my MT200's at max, and control the levels with the preamp, but just as Richard said, it isn't a good idea with a solid state power amp. The noise from the MT200 is obnoxious, because it is basically a solid state power amp with tube characteristics injected into the signal path indirectly. The tubes never get the audio signal through them, and I believe this is where the noise comes from.
I run them around 12:00 and use the preamp as hot as I dare, and that keeps the unwelcome noise down to a minimum. For this reason, I am leaning more toward a tube power amp in the future, to try to get more of the vintage type of interaction between the preamp and poweramp sections.
With the B200S, I can dime those out, and there is still less noise than with the Microtubes.
Harley