Suggestion between benchmark Ahb2, Bob carver crimson 275 and rogue atlas magnum 2 amos

Are you using a sub or pair of subs with those nice but small and inefficient speakers?

I do not see pre-out/main in on the rogue rp-1 preamp on order. That is what you would want to go out to a stereo pair of self-powered subs, send the bass load away from both your amp and your KEFs.

then, I would go with the Carver, stick with tubes to drive the KEFs, subs drive themselves.

Anyone considering a Carver Crimson should take a good look at this thread:

How Bob Carver is Destroying Vacuum Tube Audio

Since you've ordered a Rogue preamp, your best bet for synergy and success would be to pick a Rogue amp suitable to you speakers and budget.

Stretch a little for a new or used Rogue Audio Stereo 100.

Even though it is rated for the same 100 WPC as the Atlas, the St 100 sounds twice as powerful (better power supply circuitry).

The ST 100 is a reference quality amp that solid state cannot match IMHO. I had the 100 and sold it to buy a Pass Labs amp and still wish I had the 100. Just a dynamic, special sound.

Benchmark for the metas. No doubt. Should be the bees knees. Tube amps may sound good but metas not designed for those. I have benchmark targeted for use with both my metas and Ohms someday when the time comes for new amps.