Actually, I think you might be right. I've been checking on my cheap SPL meter. What I consider a loudish listening level, the readings will be averaging between 80-84 dB, with it rarely getting into the 90s. The problem is that this is A weighted, (so the unit should be dB(A)).
After looking into it, I've learned A weighting rolls off low frequencies.
I found an app for my iPad which will give measurements for instantaneous/peak measurements in both A and C weighting. C weighting is much closer to a flat frequency response, which I think is what is relevant for thinking about needed power for an amp.
The app A weighting measurement is spot on with my SPL meter...but when I have an average listening level of about 82 in A weighting, the A peaks won't get much above 90dB(A) but the C weighting goes well above 100dB(C) on peaks!
What's weird is that my amp (Kenwood KA-5500) has VU power level meters and at such a level they barely peak above 1 watt. VU meters are an averaging meter, but I find it hard to believe the amp is being driven in to clipping when these meters are down in the low part of their range. The meters have a low level setting, when put on the high level setting, which shows full scale up to 55 watts, the meters are barely moving.
Is it possible the amp is being "asked" to put out 200 watts on the peaks? (It's rated at 55 wpc). I'm not hearing any clipping. Perhaps the amp is doing some kind of "soft clipping?"
I'm listening on ADS L710, which have a given sensitivity of "92 db SPL at 1 watt RMS input at 1 meter." This seems roughly close to what I'm "ballpark" measuring.
It's a complicated subject. There is no exact specification for this concept, as it's dependent on the duration and shape of the measuring "window", the duration of the measurement, and the characteristics of the signal.
A simple approximation of "effective dynamic range" is the "crest factor"of a signal, which is the ratio of the peak level to the RMS average level.
This excellent article has an in depth discussion, and finds that the crest factor of most recordings is between 12-18 dB.
https://www.soundonsound.com/sound-advice/dynamic-range-loudness-war
The more relevant issue to this discussion is how we conceive of the "loudness" of a signal, which includes both average and peak levels, and how much demand our desired average listening puts upon our amplifier.