No, that graph is simply shown at the standard 1 watt input level(at 75dB slightly less than a tenth of a watt is used). It isn't at that SPL because that's a maximum "clean" output. The question can't be answered with precision because the amount of speaker distortion which becomes objectionable varies with the type of music(more complex orchestral music masks distortion better than a solo instrument)and with individual sensitivities.
If, distortion aside, the question instead meant how loud it could play without suffering permanent damage, that would be well over 100dB.
