Doesn't SPL also depend on listening distance and room acoustics? So, if a speaker is 90 dB/1 watt at 1 meter and you sit 2-3 meters away from the speakers, then what you are hearing is 87 or 84 dB. So, if you want to listen at 90 dB, you would need 2 to 4 watts, or more. So theoretically, a 40 to 50 watt amp capable of low distortion should do given transients.
If you want to pound your ears into oblivion, say starting at 105/102/101 dB, then you would need 16/32/64 watts using the above proportions. So, transients could demand 160/320/640 watts to keep it sounding "more live"?
So, for really loud music, a really powerful amp may come into play.
I typically listen to music at under 90 dB at more than 2.5 meters from speakers so a lower power low distortion amp should do. My amp, a Hegel h160 does nicely but it is over kill for my speakers, Focal 807Ws which were less than half the price. The speakers also do well with a really inexpensive class D with of course less quality than the Hegel. This little class D does seem to sound better in some ways to other AB amps under a grand I have tried. Depends on the level one listens, the Hegel and Focals work very well where cheaper alternatives would do for many.
I like stand mount speakers but if I were to go with a floorstander, I'd like to try Tekton Lore Reference. At 44 lbs, their doable. At 96 dB, a smaller amp or tube could do. I do stay away from low sensitivity speakers as a rule seeking something around 90 dB. Other speakers are Triangle Zetas for desktop. Less resolving, a bit more sibilant than Focals, less bass, but they do nicely as well. Don't even need a sub to enjoy them both though a sub can fill in the basslines. Other very efficient speakers I have not heard , Zu speakers seem to have a following as do others. Choices.