Power requirements can be all over the place depending on speaker efficiency, volume, room size, and even more. To get to the point, so many years ago, I had speakers with 103db sensitivity. They were horns of course. I ran SS mono blocks rated at 90 WPC, and the meters never moved, nor should they. The bass was like I have never heard since, but midrange horn was not so good.
My point is that there are too many variables to set yourself thinking about a certain amount of power before understanding the needs of your listening experience in the first place.