You'd be amazed at how low the level to cause damage can be over an extended period particularly with earbuds.
Not that 3 x 200W double stacks and 600W a side on the foldback isn't capable of some serious levels, don't worry about the audience when there's 1200W a side on the PA as well, they were there for a good time
I'm sure there a few of my vintage on here who have experienced the same type of setup