Would like your tube amp recommendation

Premium speakers require high octane power,suggest you check out Coincident Technology Dragon MK 2 mono blocks.The only thing between you and the music is air.

Have you seen this review of your speaker?

http://www.theabsolutesound.com/articles/magnepan-mg-201-loudspeaker/

The reviewer thinks they need 300w into 4 ohms to "come to life", and with a sensitivity of 85db/2.83v, which is 82db/1w because of the 4 ohm, I would agree. Some simple acoustic music would probably sound ok, but anything with dynamics would suffer.

A lot will depend on your room size and listening preferences, but the 20.1 was/is an excellent speaker, although I do agree it seems to need some power. But you can drive it quite successfully with less than 300 watts. Jim Winey used to make a point of telling me every time he saw me that the MG-20s he heard at Johnathon Valin's house sounded the best he had ever heard, driven by our MA-2s. I've also heard the MG20.7s driven by a pair of ARC  Ref 150s which worked great as well.

Whatever sensitivity/efficiency number the speaker has, add 6db to deal with the fact that its a line source and you will get a better idea of how easy it is to drive.

Most think Maggies are just fine with whatever power they are using.
I did until I lived next door to an EE professor who demonstrated to me
the difference between my 200 watts a side at 4 ohms and his 600 a side .
IMO 300 @ 4 is a bare minimum .

My Accuphase P1000 is 125W @ 8ohm, 250W @ 4ohm, 500W @ 2ohm, and 1000W @ 1ohm!! It has a beast of a power supply, and the current flows out unimpeded. But I was wondering how they would sound with PrimaLuna tube amps. Maybe I can borrow a couple from "Uncle Kevvy" for a home trial.

My Maggies are in a relatively small 12’ X 17’ room. With really well produced music, they sound great. But I wish they had a wider sound stage (I have the ribbon tweeters on the outside of the speakers), and more defined instrument placement.