REVEL performa3 f208 or TEKTON Moab

First, that krell can drive any speaker. Second, you’re in a nice situation to purchase new speakers but an even better one if you buy used. The choices in the 5k range are great. I’d say you could get a better used speaker at this price range than new. Keep searching. I have an old krell ksa 100 with some newer Sonus Faber olympicas and its sublime. You have many options. 

wow, An either or option. Hmm.....  please don’t be so lazy and limited. Take your amp and other sound equipment and go see some people that have speakers you are interested in. Don’t limit yourself, be a prick if need be, you are the customer. You got some good stuff to go tickle some drivers. Be the driver. Something may surprise you.  You are looking for the match for your system. I’m more Tekton, but that’s me.  Go and be you with the set of ears God gave you. Go LISTEN.  

MC - Your comment: "Reading through the comments its clear you either don’t know anything about Tekton Moabs or worse have been misled into believing a lot of the blather which in turn comes from people who don’t know anything about Tekton Moabs."
MC, you don’t have a clue on what good sound is. You are the person who told people your moabs were better than the $1M Wilson (Wilson doesn’t make a $1M speaker), now you are saying stay away from revel. Give it up!!!
If you want a cheap speaker that can play loud, get a Moab, if you want a good speaker up to some of the best speakers, get something else like the revel or many other brands. For example, I would take a used Revel M20 stand mount speaker over any tekton I have heard for sound quality, the M20's won't play as loud, but their sound was very very good, and that's from a 20 year old speaker.
The sensitivity of a speaker is not a show stopper. I had 86db totem speakers hooked up to McIntosh 1000 watt mono blocks and they sounded fantastic. BTW, your tekton speaker sensitivity ratings have been scrutinized because in tests, they actually have a lower sensitivity rating than company specs.

I own the Moabs and Magnepan 3.7's.  The Moabs have a very rich involving sound but the fact that they are cheaply made, poorly damped, box speakers also shows up in the way they sound.  The Magnepan's are a little less involving but technically I would say they are better if you have the space to properly position them.  I like them both for different reasons but if you held a gun to my head I would choose the Maggies first. The planar sound coupled with a pair of subwoofers is incredible. If you like tubes the Maggies aren't really an option without a much bigger budget. Ultimately, it is apples and oranges and a very personal preference.  I have never listened to the Revels or any other high end speakers except for the Spatial Audio X3's which I suspect are better than either the Maggies or Moabs but again different sounds for different tastes.

I too have heard Krell amps and Sonus Faber speakers sound quite sublime together. A combo I could easily live with. Just saying.