A buddy has a Mcintosh 402 with his 3.4s...sound great deep bass very powerful.
I have an NAD M3 for my 3.4s and the bass/dynamics are also very good (amp is brand new though and only 2 weeks on it).
At one point I connected an ARC 100.2 I once had to his s3.4s and we were blown out of the water with that combo. It bettered his BATVK500 (w/bat pak), at the bass control and imagaing and overall sound quality. Superb. The Dyns don't NEED a krell or a levinson per se, ie there are musical alternatives, but you certainly could do worse. The 100.2 was the most surprising result I have yet to encounter as it's "only" 100 wpc into 8, but it got easily as loud and dynamic (at the levels we usually play at) as the >2x power BAT.
Anyway in that price range 1-1.5 K have you considered Bryston?