Pass Labs. Some friends and I have had several amps with Maggie 3.6's (and before that, 1.5's and 1.6's). The Pass Labs, in no special order, were the X150.5, X250.5 and X350.5. All 3 were excellent in bested the others in every category, in our opinions.
I'm using the X150.5 now and it has no problem in driving the 3.6's very easily (HiFi News mag. tested the X150.5 and found it clipped at 280wpc @8ohms!!! and 380wpc @4ohms).
The other amps tried were Krell KSA 50, Classe 201 and 401, Plinius (250wpc - don't recall the model #), Hafler 9501, Parasound (200 wpc - don't recall the model #). The Plinius was second best after the Pass Labs amps.