Don't worry about playing them loud without the cap except unfiltered vinyl. I take my big Nak right up to clipping with them and have never bottomed or damaged them.
Nearly 10 years later I still have these.. I have now upgraded to 801ds
But the power needed to run these series 80s
The perreaux has something like 900w peak I had running for the past few years.. never damaged em
Still love them.. Reading this thread I will not be selling them