Stage volume can be a problem even when nothing is being said, sung or played. Think about an electric guitar running through an amp which is patched into the mixer. The amp has a natural hum about it. In this situation, the guitarist has the monitor at his feet and everything sounds great…until the music stops. I've seen this happen and under the right circumstance, it's very distracting to the worship experience.
It happens like this; the worship team plays a few songs and then the pastor walks up to pray. The musicians are still on stage because they don't know if the pastor will have them play one more song. As the pastor prays, his prayer is layered on top of monitor hum. In a large enough sanctuary, this won't be noticeable, but in the smaller venues, it's akin to an incoming swarm of locusts.
Sound tech's are partially responsible for setting and establishing a worshipful environment. (Is worshipful even a word? Well, you know what I mean.) Something as seemingly unimportant as monitor hum can shatter that mood.
There are a few ways to stop the monitor hum in this situation. Some of it depends on how your monitors are set (pre or post fade). The easiest solution is to mute the channels when not in use. Or, depending on the pre/post fade setting, you could lower the faders for those channels instead. In effect, you are also decreasing the signal set to the monitors.
Just some food for thought .