Amplifier power needed by 1.7s


I recently acquired Magnepan 1.7s along with a REL sub.
What tube amp power do they really need to perform well?
Currently I have a MAC MC275 and am acquiring a second to run them as monos. Will this be adequate? Room size is 20x30 with 1.7s about 4 ft. from short wall. I listen about 11 ft. from 1.7s.
128x128wfmayus
I heard the 1.7's with and without a rel sub. Addition of the sub made the 1.7 a much better speaker. I was very impressed. I'm not so sure that tube amps are the answer. I prefer SS with maggies. I'd go for tubes in the source or pre.
Somehow (in my first response) I missed that you already have a REL sub. Everything I've read (and heard 1st hand from an owner of 1.7s and a Rogue Cronus Magnum indicates that that is an excellent amp/speaker match. After that, add a second matching REL sub. Two subs blend easier and give you more options for smoothing out room node resonances.

My experience with twin subs matches Auralone's. I started with a single sub in November with my 2-channel system with Mirage speakers. Three weeks later I added a second. Adding the second one unexpectedly resulted in much more 3-dimensional imaging and more perceived space around the voices and instruments.
Thanks to all. Being new, I'm not sure of the etiquette but this might be a good point to wrap up this thread. Lots of good info. and thoughts. I now have an idea of where I'll go from here.