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 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!!