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.
I've heard the 1.7 (no sub) with the 90wpc Rogue Cronus Magnum and it sounded very good.

Thanks for the input. I"m under the impression that the newer MC275s will actually do about 90 wpc. Maybe one will be adequate if 90 wpc will do the job.
I chose the Mac amp because I've found I prefer the warmer side of neutral. It turned out not to be as warm as I expected, but that is an amp issue, not a 1.7 issue
Thats a large room, how loud doyou want to play your music?

Going bridged mono opperation will give you some benifits. Please do not under value acoustical room treatments. That can make a bigger change and improvement in sound quality than simply changing components. I have had 1.7's and they can give you the "you are there" experience if properly integrated into your room. Definately try moving your 1,7's and your listening position (key). Also, try tilting them forward a bit, this made a noticeable improvement in my room with my 20.1's. I also have had a leap forward in my sound quality replacing the stock Mcintosh tubes in my 2301's and c500t preamp with Gold lion tubes. Hope this gives you some ideas....enjoy your Maggies!
Wyred4sound works well on the 1.7s and the price is right for the amount of power (1000 watts @ 4 ohms). The Maggies love all of that power and you won't need the sub.
I think your room size (20x30) stretches the intended volume for 1.7s. The Cronus Magnum IS a great fit for this speaker. The Absolute Sound used that amp to review the Maggie 1.7 and came away all aglow. I told my audiobuddy (who owns 1.7s) about the Rogue Cronus Magnum, he bought one and absolutely loves the pairing.

Since you are listening at 11', the Cronus Magnum may be enough, but you may want to add some subs to flesh out that 4800 cu. ft. space. My audio buddy matched these SVS subs to his 1.7s and likes the combo very much.
Thanks to all for your thoughtful (and helpful) suggestions. I do not listen to much rock nor do I like ear splitting levels. Prefer acoustic vocal, jazz and orchestral music played at reasonable levels. In the past I have used very high output SS and 'stats. I found it very revealing but somehow fatiguing when listened to for an extended time. I find that source material becomes much more of an issue as such a setup is brutally revealing. There just seems to be something about tubes. There's so much poorly recorded material out there. Source is a modified (R.A.M.) Oppo CDP direct into amp(s).
I have the Maggie 1.7s with an Audio Research DSI-200 and two REL subs...a good recording will not sound edgy or brittle with this combination...tubes only smoothed out the crap recordings while losing some detail in the excellent ones.
Thanks Auralone

Two REL subs! Do you find using two worth it? I've read discussions on this and opinions seem to vary widely. I've had ARC gear and it certainly is excellent and I would be surprised if you were anything but happy with it.

The effect of tubes seems to agree with my impression of their effect.
I had one REL sub and after six months added did make quite a substantial improvement in depth and ambiance retrieval. I've spent too much money over too many years on trying to make a silk purse out of a sow;s ear (attempting to make horrible recordings sound good on quality systems with expensive tubed gear). And don't let anyone tell you that Maggies do not need a sub!!
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.