Tube amps and speaker ohms

In your opinion , do push pull amps work better with 8 ohms or 4 ohms. .I am under the impression the lower the ohms, the more power is demanded from the amp....Another question, are there low powered SET amps ,and high power SET amps?
I'm looking at a 40 watt 845 tube amp for my 8 ohm, 89 db speaker.. just cked the Thor has a 86 db W18 midwoofers(2 per cabinet) and a 88 db tweeter. Will an 845 amp rated 40 watts be able to drive the 86/88 db speaker? With authority, bass, mids, highs, in dynamic sound stage? Synergy? Or poor match?
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+++ We are more interested in which labs are actually producing a tube amp to meet demanding power hungry speakers. +++

The best amp for meeting the demand of power hungry speaker is called a transistor amp. A person attempting to use a tube amp on said speakers is called ignorant (I am being kind)

+++ I am only interested in the end result. +++

No, I suspect you are interested in your own opinion ...

Yeah but can they produce a musical image equal or similar as does 2 tube amp labs that i have in mind. Its all about who can get closest to the high fidelity musical image. Audiofeil feels since i know nothing of the tech side and so suffer from deafness. 30 yrs audio critque and now I am deaf.
Dear paul: The statement is totally accurate, it is not talking about " speaker has a benign impedance curve across the frequency range. " like you state.

regards and enjoy the music.
Paul , ss amps may be the "ideal" for demanding speakers, but since I do not care for ss amps, I look for certain tube amps that can carry a relatively heavy load. I agree stats/panels/ribbons need ss current for optimum response. Vandersteens need good ss power as well, at least hios larger models. TRhe point of the topic was to ask the GENERALIZED question that tube amps prefer 8 ohm speakers(though even 8 ohm speakers can dip to 4 ohms on huge orchestral challenges). I think the consensus agreed, though some here want to split hairs and bring up their special agenda and objections. Which is fine. I'm staying with 8 ohms, and thats that.