Although this case doesn't make a lot of sense to me - and I wonder how much of what you report is subjective in nature or how much of it I would hear if I auditioned your set up - I suppose the remote possibility exists that what you're really not liking is that the more powerful amps are actually controlling the speakers' drivers *better* than your older amps. Maybe these speakers are apt to sound a bit 'looser' with some amplification, and you enjoy the way they sound more as a result. If so, you might be able to make an improvement by repositioning the speakers.
I have to admit I find this explanation somewhat farfetched, but I also have to admit that when I used to work in a shop that sold Snell, I never liked the B's much no matter what amps we put with them (and we used Levinson, McIntosh, ARC SS amplification of up to 400 watts.) But, my complaints about them were almost diametrically opposed to what you're describing, so I'll demur. Sorry to criticize a speaker you've liked and own, but to sum up, I think your new amps must be fine, and you might want to start thinking about looking for new speakers.