We toss a spare SM58 over a truss in the ceiling about 4 feet out from the frontline at stage center and 8-10 feet high and run it to a MUTED (important!) channel on the mixer. The room ambiance can then be mixed to taste for each IEM aux mix. No more room isolation. No more problems hearing the crowd, requests, etc. Adjust the ambiance to taste. I highly recommend trying it.
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