We're looking at IEMs. As an interim experiment, we've got the drummer on headphones now. He is very happy.
Part of the migration to IEMs (In-Ear Monitors) is providing each musician with their own volume control. In fact, with their own little mixer so they can adjust to taste without having to get word to the FOH mixer. (There is no monitor mixer in smaller houses).
What I've done for several previous shows is: run 2-4 channels of monitor back to the pit, and set up a micro-mixer on a rehearsal cube. That runs to powered monitor and/or headphones. The easiest instrument to add is that of a keyboard player; you just y-cord it right at the DI box.
In this case, the drummer is getting keyboards (over a y-cord), the same vocal bus as the conductor (contains every open wireless microphone), and for "more me," I set up a pair of overheads and hard-panned them left and right. I tried the rig myself, and I'm no drummer, but I really felt like I had
ears in the space instead of being inside headphones. But vocals, and
the conductor's keyboard, were still coming through nice and clear.
Close-mic wasn't working anyhow. There's too much variety in what he does, and it was leaving ride and tom out of the picture anyway (not enough input channels). So it is now a pair of condensers at about two feet overhead; one over the hat and one over the ride and both equidistant and pointing
at the snare. It isn't quite the tight sound I want for the more "pop"
parts of the musical, but it does a lot better at capturing the variety
of things he gets into during the show.
When we get into IEMs, we are probably going to be able to send a pre-processing clone of every pit input back to the IEM master, and then using something like the new Behringer jobbies, make custom mixes for each musician at their station.
And one of the channels on that system will be ambient/talkback, so the musicians can hear each other and the conductor can say, "She's off again; quick, back to bar 44 and vamp on it" or, "No, no, concert Bb."
And maybe even I or the FOH de jour can be on this loop so during tech we can actually communicate.
The two goals are, of course, for the musicians to be able to hear what they need, and to reduce wherever possible the backline contamination. For most musicals I've done (in a multitude of smaller theaters) in the top three has been keyboard monitor leakage (vying for top spot, usually, with bass amp leakage and drums). And by the time you reach the five worse noise-makers in the pit, include the vocal monitor from stage to conductor; in many small shows, I've fed back on the conductor's monitor well before I've fed back on the mains!
The problem is, acoustic musicians on headphones are going to be no more conscious of how much sound they are pumping into the air. Putting headphones on the band may keep them from blasting the audience with their monitors, but they are still going to blast the audience with brass and drums. And it will still be a chore to try to get a balanced sound out to the audience.
At least it beats what happens with monitor speakers. What has happened there --more than once!-- is that the conductor turns the
vocal feed all the way up until the pit monitors are feeding back, then
starts whining he can't hear his own keyboard anymore, and runs out and
buys a new and bigger keyboard amp and points it at his ankles turned up
to 11... at which point you can't hear the rest of the band, or the
singers, and I can't even bring up the vocals because they are feeding
back via the pit.
At least with in-ears, the only people that will go deaf is the musicians. And the good models even have limiters to (partially) protect them from themselves.