Keep cranking it until you get the meter reflecting sustained levels at 115 db SPL. If it sounds clear and clean and undistorted (but obviously very loud) then you can be assured the speakers are fully capable.
I’ll pass on that :)
What I stated is that on the basis of my speakers rated (manufacturer specs) sensitivity and power handling capability, they can produce over 115 db. Besides, even if my speakers cannot attain that decibel level, I would still consider them "fully capable" because that level is a bit unrealistic.
Additionally, I live in a coop. I do make an attempt to show some respect towards others. My neighbors already endure the fact that most of time (I listen 3 hours per day) I listen to Grateful Dead, which sounds realistic from a live concert perspective topping off around 95 db, often even lower. On lessor occasions I’ll listen to Nirvana, AC/DC, Deep Purple and a hand full of other select choices that "warrant" playing at louder (compared to many other bands) levels. Even in those cases I’ll top out in the low 100s.
EDIT:
And if I'm not mistaken, 115 db is "dangerous to the health of ones ears" if sustained for an undo length of time.