I tried maxing out the master and preamp on the amp and run the mt-2 as a boost with level maxed out and distortion at 0. It gave a fat heavy distortion. It is freaking loud though; so yeh, I have to be content with what I get at lower volumes.
sounds counterproductive - if you're looking for metal, i'd advise trying it the other way around. higher distortion, lower level, adjust amp volume to taste.