best amp for Magnepan 3,7

I'm running my 3.7s with a VAC 300.1a (150 tube wpc). My room is 18x25 with pitched ceilings. No clipping, no distortion, no running out of steam -- tight present bass too. I don't like to listen at volumes that damage my hearing though. Another option is hybrid tube amp like the Moscode 402.

More power is always better in my experience, my top choices for your Maggies:

Pass Labs X-600 (.5 if you can)

Pass Labs X-350.5

Sanders Magtech

Cary Audio CAD 500MB's (what I use with my 3.6Rs)

Bryston 7sst2

Parasound Halo JC-2

Wyred4Sound 1000's

I've had all these hooked up to my Maggies (with the exception of the X-600's, and the Sanders, but I had an older Sanders and give the new one some love for that). I have had a few other amps on them as well, but I wouldn't put them on the list.

McIntosh mc2301's. I have tried many amps, it was immediately clear that the big tube amps were a perfect match.

System synergy and room characteristics will influence your results to such a large extent that only an in home audition of the amp(s) under consideration will be of any value.