I stand corrected. What i mean to say is that on most speakers, SET amps, 300, 845's will not provide the current necessary to produce tension, "slam". I've had KT88's in my JOR and the result was total failure. The amp lost all its "authority". So I also place KT88's in "SET" category, even on a push/pull design. I have not heard the Cayin KT88 yet, that might change my opinion. Point is, some tubes in many designs do not offer the body in MOST speakers that a decent ss amp will offer. Put any SET amp with a Vandersteen and then put a decent ss amp. SET's will not drive the speaker. Tubes can make great music, that is IF you can find the right speaker. As you point out its a combination of the 2. Much easier done with any ss amp, tubes work only with certain speakers.
Please correct if/where I err.