My experience is that it depends on the nature of the individual running the room. Some guysEdgar, for example, is there to wring out the best they can get from one system in a given room, so they don't want to mess with it when they ahve it dialed in. Others want to hear a variety of interactions of gear and have fun with that. Once you can tell that interest is waning in a setup, it's fun to mix it up......