if you can get your hands on a cransong stc-8, that thing is wicked
transparent.

even if you mult with different gain stages, you'd probably go
unnecessarily crazy trying to match them up later during editing.

have the guy play/sing his loudest he thinks he will do, then if you
could have an stc-8 or two around to catch the would-be overs, you'd
be in really good shape.