Join Date: Mar 2007
Location: Canandaigua, NY USA
My experience is that claims for huge amounts of headroom can't be justified. As said above, the source technology places its own limits on the maximum signal peaks. About the only exception I can think of is running over some rock or dust boulder in the groove of an LP. Those pops can be substantially beyond the music in amplitude and slew rate, and the front end of the preamp has to deal with it or at least recover elegantly.
I don't know if it's still accepted, but I've always heard and adhered to the following: AC voltage measurements are always assumed to be RMS unless otherwise specified.
May the root sum of the squares of the Forces be with you.