Brandon, you used the phrase "before distortion" as the standard, but as you know, speakers exhibit substantial distortion at a point where the electronic components still have distortion levels far below audibility. For example, note that the
M80 test at 95dB by the NRC showed that at 200 and 2000HZ distortion was beginning to appear, being about 40dB(about 1%)down. There don't appear to be any published tests of distortion at still higher levels or any definitive reports of the levels at which it becomes clearly audible. Certainly it would be higher than 95dB and much higher levels are possible before the speaker would suffer permanent damage. It can be noted that, driven by 1,000 watts, which has been exceeded in testing, the M80s would have an output of about 120dB, apparently without that permanent damage occurring.
Another point raised by your question is that hopefully those 100dB plus levels you mentioned were experienced only briefly, since generally it's cautioned that levels over about 85dB on a long-term basis(e.g. even when using power lawn mowers)make hearing protection advisable to prevent permanent damage.
