Tubes and less sensitive speakers

I agree - nice job by both in providing clarity and reaching a unified view.

Regarding proper subwoofer integration, I would caution that while this is a valid approach, in my experience, it can also be quite challenging due to the true dipole dispersion of Maggies. A number of years ago I was running a set of Quad 2805 and Maggie 1.7i with Atma-Sphere amps and wanted to supplement with subwoofers. Unless the subs were truly fast enough to match the speed of the stats and planars and impeccably integrated, it tended to cause smearing through the frequency extreme because of interference between the subs and the speakers’ radically different rear dispersions. In my opinion it would be best to first address the amp / speaker matching to the best of your ability as this will deliver the optimal control and tone out of the speakers. Doing so will also make it easier to integrate subs if/when one is ready to do so.

In short, don't use subs as a band-aid solution, but only to improve upon performance that can already be gained elsewhere.

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.

Thanks for all the info and opinions.  I admit I have a case of upgradei itis and am approaching this with caution.  I am also considering Magnepan's new X models from which I have heard very good reports.

The Music Reference RM-200 MkII might make for a nice amplifier choice for Maggies as @bdp24 noted. One of the reasons is that it is one of the few if not only amplifiers with a tube output stage that outputs more power into lower impedance loads. As measured by Roger Modjeski on his bench the amp puts out 112 watts into 8 ohms, 145 watts into 4 ohms, and 125 watts into 2 ohms.

Regarding the poet by @blisshifi: Mating subs with Maggies (in fact any and all dipole loudspeakers) is indeed a challenge. The solution is a dipole subwoofer, which Magnepan has been working on a for a few years now.

There is already a real good one available, the Rythmik Audio/GR Research Open Baffle Servo-Feedback Subwoofer. It employs two or three (your choice) 12" servo-feedback-controlled 12" woofers in an open baffle frame, and works splendidly with dipole loudspeakers. Check the GR Research website for details.