Volume level for slightly overpowered amp
I have bought an amp that outputs 125 watts per channel, connected to speakers that are rated for handling 100 watts per channel and recommend amplifiers of 40 W to 100 W.
I understand that this is no problem as long as I don't crank up the amp's volume too much. But my question is, how much?
If I understand the amp's volume setting to be linear with the number of watts, then I would be able to crank it up to 100/125, i.e., to 80%.
But I have also read that perceived volume is not linear with watts (large differences in watts create relatively small differences in perceived volume). Then if the amp's volume setting reflects perceived volume, it wouldn't be linear with respect to watts either, so I probably would be able to set it to a bit more than 80%.
My question is, which of the two assumptions is true? How far do you think I can move the volume setting while being safe not to damage the speakers?
Note that I'm not crazy for a bit of volume. I mean, if the answer is "80%" I'll probably not go over 75%, if the answer is "90%" I'll probably not go beyond 80-85%, just to be on the safe side. But I would know what the safe side is a bit better if I knew where I stand, anyway.