Yyzsantabarbara hi.
The Kef Blade II are hard but not too hard a load to drive at 87db and 3ohm min right across the low to mid bass. And there are no nasty - phase angles to worry about.
So a very good 4ohm capable amp would do, I myself would be looking at Pass Labs XA class of amps.
I do not think class D has come of age yet, as the switching frequency technology is not yet high enough.
Another amp worth looking at is the Parasound Halo JC1 mono-blocks in their higher Class A mode that's switchable on the back, I listened to these on a pair of Wilson Alexia's, a real evil load (.8ohm epdr), and they sounded great with this amp.
Cheers George