I don't know what the impedance curve of your KEF's looks like but if they are not to tough of a load I would look at Atmasphere's OTL lineup of amps; if you have never heard OTL amps you owe it to yourself to at least hear them.
Best Tube Amp under 10K?
Having every audio dealer in town recommend their line as "the best unless you want to spend $25K" and buy a ..." is frustrating. Well, like most of us, I can't spend $25K on amps ... but I am curious to know what others consider their "final" amp upgrade under $10K. My listening tastes are wide ranging but will mostly include SACD jazz and classical. I do not have a turntable ... yet. And I ususally play at low to moderate volumes only (the wife factor)-- speakers are reasonably efficient 91DB KEF Ref 4's that I hope to upgrade.