I have a full range speaker of 92dB sensibility.
I run an EQ to have a quite flat frequency reponse. It is at 0dB around 100Hz and at -20dB around 8kHz.
So I need 100 times more power at 100Hz than at 8kHz.
I was thinking that if I listen at 80dB average with peaks at 95dB, I would need 2 Watts at 8kHz then 200 Watts at 100Hz.
Can't be calculated unless we know the distance you are from the speaker.
A 3dB increase represents a doubling of the power. The power required varies as the distance squared from the speaker.
Hence a 20dB difference is as you say close to 100 times the power difference, yet how much power is in the music signal at 8 kHz or beyond, well it depends on your music, but most likely less than a few %, frequencies less than 1 kHz is where most of the power for music goes.
92 dB figure you give is for 1W@1 m(possibly for 1 kHz) Your frequency response sounds interesting, either the bass is down or the high end is up, but Im guessing the 100 Hz sensitivity wont be too far off the quoted value) you dont state how you got these values(doesnt sound like one of those autoanalyses as they wouldnt be quoting at 100 Hz) is this a number just generated from a 100 Hz tone? could be just a dip due to room dimensions if done at singular frequency.
So if you listen 3m from the speakers, you will need 9 times as much power as from 1m to create the same SPL, or 9W to produce 92 dB at 3m
of 18 W to produce 95 dB at 3m. (would only need 9W channel given/assuming you are using two such speakers)
200W would put you at about 10m from the speakers to produce 95 dB
for my own speakers which have a 80 dB rating, 12 dB less than yours effectively means I need 16 times as much power for the same volume. I need about 300 W at 3m for 95dB, hence why the lost cost and high power output of the crown makes sense for me.