How do tube Watts compare to SS Watts?

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.

Bartok, the KT 88 (similar to 6550), etc aren't push-pull. They're pentodes. Push pull is an amp circuit config.Cheers

I thank all of your for sharing your opinions! The Theil 2.2s are presently driven by a Conrad-Johnson 80W ss amp with a C-J tube preamp. This is more than adequate for the music and volumes we enjoy. Using the ss W to tube W factor of 0.5, roughly, 40-50W tube might work; 60-75W very likely will work. I'm hoping to get something definitely warm not neutral. (I've always preferred the tone of Fritz Kreilser over that of Jascha Heifitz.) Ilooked into the Jolidas, and they are certainly impressive. But I've noticed that some folks think that they are not particularly warm or "tubey." I can't say and they are not available around here for roadtesting. Given constraints on tone, wattage, and cost, I think I'll nose around for early '60s American amps that have been, at least partly, refurbished. Or...maybe back to the Jolidas. Thanks again. Rascal

Greg, thats interesting. Not sure what a pentode is. Is the KT90 a pentode? If yes then all these 3 tubes are used in amp circuit designs that are different from SET designs using the 300 and 845 tube. Rascal, I also prefer Kreisler over Heiftz. Oistrakh was my prefered violinist, but I recently sold off his 6 cd set In Prague, oop. The set had too much romantic era stuff, which I don't care for. I love Gideon Kremer's recordings, except the Schnittke 4 vc's, which fault lies with Schnittke. Even though Schnittke is one of my top fav composers, his 4 vc's left me uninterested. Read my reviews on amazon.

Bartokfan. A pentode is a vacuum tube that has three grids, namely a control grid, a screen grid and a suppressor grid. The screen grid was added to isolated the control grid from the plate to reduce Miller effect.

A tetrode is a tube that has a control grid and screen grin (no suppressor grid). The suppressor grid is added to reduce secondary emissions from the anode.

A Triode has no screen or suppressor grid.

Triodes, Tetrodes and Pentodes can all be used in a push-pull or single ended configuration. When used in single ended configuration they all have to run class A, in push-pull they can be run in either class A or B (or combination thereof.)

Tetrodes and Pentodes have their screens grids biased to +. If you bias the screed grid from the anode, it is know as triode mode. If you bias the screen grid from a tap on the primary winding of the output transformer, it is called ultraliniar mode. If you bias the screen grid from the power supply, it is called tetrode/pentode mode.

The method of biasing the screen grid alters the character of the tube slightly. Many amps have a switch to toggle between two of these modes.

A KT90 is actually a kinkless tetrode (the KT stands for Kinkless Tetrode). I believe that is actually a pentode with the suppresser grid tied to the cathode. And EL34 is an example of a pure pentode.

Regards
Paul