I did Live Sound Engineering for the Brothers Four in the late 70's/early 80's as an independent Sound Contractor in relatively small venues in the greater Seattle area. I'd discuss with them in advance of their shows and tell them that I wanted to get the Front of House Fill to just basically take care of the room, after that, they were welcome to increase their volume on stage to provide additional fill as they saw fit.Unfortunately I learned that as a teenager when my grandfather passed.
I have been making digital copies of a lot of them since it is hard to find modernly published music by some of these artists. New Christy Minstrels, The Brothers Four, etc.
That and copies of the historical family pictures including names and dates.
I did, they adjusted as they saw fit and it worked out very, very well. Some of the best/most enjoyable sound that I ever mixed.