KEF R7 META

They're being driven with a Pass Labs INT-60 integrated, which is supposed to be 120 watts into 4 ohms.  My experience is that this works well, I can get near 100 db in my room, which is more than enough for me, but that would be pretty much all cranked up. Were I to do this again I might go with the INT-250 but I'd have to say I'm happy where I am. The sensitivity is fine for most applications but you're correct about the impedance. Most of my speakers in the past have been dipoles or open baffle and I wouldn't mind doing that again (with way fewer watts and tubes, likely), but I'd have to say what I have now is probably the best overall the cleanest sound I''ve had so far. 

@howardlee I'd say use the Pass labs as Preamp and get two of this Monoblock that is stable down to 2 Ohm. With incredible current drive and stable at all loads so are not load dependent.

Have tons of voltage swing to make sure the speaker movement of cone is aligned.

Get two of this - https://www.buckeyeamp.com/shop/amplifiers/hypex/ncx500/monoblock

Power delivery: 700 watts @ 2 ohm, 700 watts @ 4 ohm, 380 watts @ 8 ohm

You have so much headroom with this that you'd never lack for power delivery.

You'd connect them through the XLR Preamp Outs on the INT-60 and carry that signal via XLR interconnects to each monoblock XLR input.

Get two of this cable. Robust, does the job and doesn't get in the way of the signal - https://www.amazon.com/Units-Balanced-Microphone-Amphenol-Connectors/dp/B074XSDCG6

We've got two systems, KEF R7Metas in the second system and Tidal Piano Ceras in the main one.. The R7s are in a 30' x25' room with 10' ceilings and well away from side walls and the rear of the speakers are about 32" from the wall. 

We use them with a variety of tube and solid state preamps and amps. At present, they're driven by a Modwright ls99 preamp, Luxman M700u amp, and Auralic Altair G1.1 streamer. The 120 watt/8ohm Luxman drives them as effortlessly as a pair of PS Audio M1200 mono amps with 600 watts/8 ohm. A 25 watt/8ohm Decware ZenTorii tube amp sounds pleasant but doesn't really get them energized well. The Luxman M700u, PS Audio M1200 monos, and ModWright KW99 mono amps all sound excellent with the R7s but I slightly prefer the Luxman. The R7s need to be pushed a bit to get them sounding at their best IMO. At low volumes their ability to render instrumental timbre isn't as fully realized. They are very revealing of the quality of the equipment and cables downstream and need excellent partnering equipment to realize their potential. They sound better than most any speaker in their price range that I've heard at several audio shows, at least to my tastes. They  don't perform at the level of the Tidal Pianos in the ability to render instrumental timbre and minute nuances of performance details but they have a wider sweet spot for more than one listener. I've yet to hear anything I'd want to replace them with at anything close to their price.