Can anyone explain what a power tube does inside an amplifier, eg kt88.

Why is it necessary to have eight Power tubes on a mono block amp? Assuming its 300 watts, does this mean each tube is incrementally amplifying the total watt availability? Why not just do a few tubes, or would that means less watts available?

That's a lot of vacuum space for electrons to flow through going through so many tubes so quickly. I recall seeing one amplifier with a single tube about eight times the size of a kt88.

Takes space for all those sweaty little charged particles to do their thang...😏

SS stuff makes the work easier....and less expensive...

Well, originally...anyway...;)

"Why is it necessary to have eight Power tubes on a mono block amp?"

A KT88 tube is rated at about 35 watts per tube. That is why you need 8 tubes to produce 300 watts!

So is each tube individually responsible for incrementally amplifying signal?? I believe all eight tubes would be on the same circuit.

Just like a Christmas tree lighting system?

There's a reason why the Brits refer to vacuum tubes as valves....it's a bit more visually comprehensible.  The smaller signal input to the grid modulates the current flow from cathode to plate and through the output transformer.  It's akin to mechanical leverage where a small action can be magnified.  If you want a thorough understanding of how tubes work in various circuits, pick up a copy of Radiotron Designer's Handbook.  It'll keep you busy for a while.