WHAT'S THE DEAL WITH WATTS?

I’m considering acquiring a new (for me) integrated, under $2k, to drive my KEF full range speakers. They are very efficient (93db) , 4ohm and rated for 50 - 200 watts. It seems that a good amp with 80 or 100 watts per channel at 8 ohms will take these speakers to any volume I’d want...

I agree with others regarding an amp that can produce high current and preferably double down in its 4ohm power output. Or at least come close.

You know the speakers are 4ohm rated, yet you say that an amp that is rated 50-200 wpc into 8 will get the job done??? Not necessarily if the amp does not have its 4ohm specs published. It could have a compromised power supply and not be able to generate the current needed to be stable at 4ohms. Just make sure the amp has a 4ohm rating too and because the KEF’s have high sensitivity, you’ll have no problems. There are lot of good ones out there in your price range.

My bad; these speakers are rated for maximum 300w at 4 ohms.

IMO, power handling ratings for speakers are among the most meaningless spec there is.  Impedance and Sensitivity are the specs that matter most.

At 93db sensitivity, a good 100 wpc amp into 4ohms will drive them to ear splitting levels in a medium sized room.  You do not need an amp that will produce 300wpc into 4 with these speakers.