How much amplifier power do you really need?

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Here's an interesting blog post I stumbled across while looking for something else: https://www.kvalsvoll.com/blog/2018/12/0...do-i-need/.  This is written by someone who sets up sound systems professionally for homes, media/music rooms, and small cinemas.  It covers much of the same ground as this thread (albeit in a more compact form...) but this section stood out particularly:

Amplifier power must be dimensioned for the peaks. The rms power will be much lower, but we need to be able to reproduce all peaks with no clipping and compression.

If the music has a crest factor of 20dB – normal for good quality recordings – then the actual power to the speaker will be 1/100 of the peak power, so that a 200W amplifier operating at its limits actually delivers only 2W power that goes into heat. Even with very loud and compressed recordings, with crest around 10dB, rms power will be only 20W. Amplifiers are usually dimensioned with this in mind, so they will actually overheat if you try to draw max power continuously over some time.

It is the most dynamic recordings, often with acoustic instruments, that will test the limits of your power amplifiers. Nublado by Sera Una Noche is never too loud, even though the peaks will use up all available headroom.

Much of that is not new for anyone who's made it this far, but the comments about 20 dB crest factor being "normal for good quality recordings" and acoustic instruments being particularly demanding caught my eye.  (Sadly the Sera Una Noche album is currently £133 on Amazon so not something I'm planning to try out in the near future...)