The way it's done in most professional situations is to use a
cue light and a
handset on the com pack.
Cue light gives you: A)signal for playback cues that the SM needs to
cue, B)
call signal if the SM or somebody else needs to talk to you on Com (the SM will rapidly flash the
cue light, to get your attention and distinguish it from a normal
standby light.
Then on the ClearCom station you have a
handset (looks like a telephone
handset, but it has a big push-to-talk
button on the
grip. This way you can pick it up, hear what you need to, talk if you need to, and then put it back down and go back to mixing the show.
Somebody mixing a show should never, ever be on
headset. An operator on a playback show, with no mixing involved, it's slightly more arguable, although at most it should be a single-muff lightweight so that at least one ear is open to hear the sound (particularly important in judging
fade rates).
--A