Guidocorona,
Thanks for the answer. No need to apologize for being unscientific, this isn't a classroom. Just to clarify, your description of treble IM, to me, sounds like its a matter of getting timbre correct. Not an easy thing to do but its extremely important.
Feds,
The above comments make me think what it is that I like about my Rowland 112. When I first got it, I definitely thought it was rolled off in the HF's. The more time I spent with the amp, however, made me change my opinion. All the information is there. Cymbals sound like cymbals and not like you took a piece of metal dropped it on a hard floor. I'm pretty sure I was mistaking the amp being rolled off, when it was just doing a very good job of making the HF's sound like what they are supposed to be, instead of noise. The amp does have some flaws, though. Thats why I was curious about your 102.