@cb3489,
I’m a very happy owner of an 8 watt 300b SET amplifier. The KEF  is a 4 ohm speaker that dips to 3 ohms in the bass frequencies. They recommend 50 watt minimum to drive them. In addition it’s a 4 way speaker with multiple crossovers. In my opinion this is not an ideal choice for a low power SET.

I believe you’ll get much more of the capability and attributes from a 300b SET paired with the Tekton Perfect SET 15 speakers. They are intentionally designed to work very well with low power tube amplifiers.
Charles
i agreed. I ordered Tekton perfect set 15 a couple of days ago. 8 to 10 week delivery estimate. I am  also planning to buy Muzishare X9 as well soon. 
Also let me give some more info about kef 104/2 and 105/3 and tube amp triode mode 24, ultra linear 45w kt88s. In triode mode 1 or 2 o’clock area i assume 12 14 watt kefs and muzishare x7 shakes the house and i feel the bass in my lungs. But i like low watts with full air music so that is why i am still experimenting to go to 8 wattsh set and tekton 15 inch woofer 8 ohm stuff. For someone wants loud music these amps and speakers combinations seems to be pretty satisfactory. 
Yep, the KEF is rated at 93 db sensitivity so with even modest power, reaching high volume would not be a problem. And no doubt that the push-pull KT88 amplifier is more suitable than an 8 watt SET  amp.
Charles