A speaker so small does not need much in the way of power maybe what you really mean is power of sound and that you will need a more big speaker or add a subwoofer or two to the kef's you already have.
I need more Power Scotty !!!!
Have Kef LS 50s Outlaw RR2160 receiver. Technics SL D2 turntable. I love my system sounds fabulous. Looking at Emotiva Mono blocks. Something under 2K would be nice. Lastly I am a retired Physicist so no upper mid range breath and air considerations. Love the site. Regards Pat Orlando.