I've reached 105dBC in my system will ALL speakers & ALL subs playing, but not with one speaker.
I think in 2.0 (2 speakers playing at the same time, no subs), I've never exceeded 92dBC because the midrange and treble beyond this SPL would be excruciating to me.
I think THX reference peak of 105dBC for ONE speaker and 115dBC peak for one sub is a limit that most people will never reach because their ears (and wives and relatives) would say, "Turn the damn volume down, you nitwit!."