Thanks everyone for your recommendations!
I'm not planning to move anytime soon - so power should be enough with either amps for now. I'm more concerned about the overall sound quality of the two amps, for now given the fact that a future speaker upgrade could reveal more sound qualities than the CM1 are doing now.
So the H190 is overkill for the room and maybe the H120 is too but what about their sound? I can't find any significant information about a design change from one amp to the other that could "objectify" a step forward in SQ.
I know that listening by oneself is the rule of thumb but after several tests I'm beginning to be a little confused so other people opinions could help.
The H190 sounds a little better to me with some tracks but it may as well be placebo effect...
Or maybe the way to go is to upgrade the speakers first, then find the right amp!