Hi Ralph, my experience is a bit different than yours. More often I hear "softer" (smoother, less grainy) treble presentation with (fullrange) ribbon speakers. For example years ago I heard the Dali Megalines (ribbon tweeter + midrange with cones for the bass) and it was as if there was no treble, at least not the treble we are accustomed of at home. The sound wasn't dull either but quite natural to me. The problem is at home we hear another sort of treble/high frequency reproduction than in the live situation --> live music sounds much more "smooth" and airy in the high frequency department.
Chris
Chris