I have habitually bought double the power that I would ever need. 100 watt rating, in the places where I have lived, using the speakers I have owned, was always pretty much ridiculous. I do listen at reference levels and beyond. It's where just about all the speakers I have owned really sound their best. Everything about them just seems to balance out at that level. I just always (before internet) assumed that the speakers were designed to be at their best at these levels. Even now, without measuring db, I will end up within a half db of the same SPL by ear, somehow. It seemed that this is where the recording engineers, equipment manufacturers managed to all come to an agreement somehow, or seemingly like about the only hope for some sort of unsung, default, universal standard.
I didn't have time to do all the reading it used to take to hash all this stuff out when the information was only in print. Nowadays, we can research this stuff instantly. But now, I am too lazy to care. So, I just buy double the headroom across the board, and never really have to look back.