Plinius SA-102 for Magnepan 3.6

I'm sure they will run them but not at optimal performance. I believe you'll need more power. Usually a safe starting point would be 300 watts/4 ohm. The 3.6's are "clean power" hungry speakers. You have a nice sized listening area too!

As Lak said ... but, if you want, you can get a second 102 and bridge them for a balanced 400 watts. The only problem with that is so much gain that the volume knob won't get much work. Neither will the furnace.

I matched my 3.6 with CJ premier 140, and never had feeling need to more power. In the same time also owned 20R.
CJ 140 tube watts were to low for biggest Maggies.
I have got excellent results drove 20R with my Plinius 250 mkIV.
I am sure your Plinius will work well with 3.6

I have been driving my 3.6R's with a pair of Odyssey Stratos Extreme Monoblock SE's with great results.

i own the SA-102 (presently driving M/L Vantage's) and my room size is 14'4" x 23' x 8', prior to my M/L's i owned Maggies for twenty years. I think your SA-102 will do fine, it's ability to operate in high bias Class A will allow it to bring out the best in your Planar speakers. I can honestly say I have never heard a better amp at or near it's price point !!