Also to answer the OP's original question, Audio Research and Magenpan have have had a nice love affair going on for some time now, so perhaps look into their amps.
I agree that with Ralph that if you're using the 3.7's and want to look at Atma-Sphere, look into the MA-1 and not any of the smaller models. I've been in the camp of trying to mate his smaller amps with autoformers on larger planars / stats and while it's pleasant, you won't get the best out of them. The MA-1 MK3.3 is highly recommended as long as you can handle the number and heat of the tubes.