The DCA isn’t supposed to do anything “when the actors all sing together”, it’s supposed to invisibly control the level of input faders when you physically move the DCA fader. It isn’t a compressor, it doesn’t do anything automatically.
If you did turn down the DCA, how do you know that the send levels to the band didn’t change? Reports from the band? You maybe just don’t agree on how much quieter it was supposed to get. 🙂
If you turned the DCA down and the channel post fade send levels didn’t change you may not have had the send actually post fade like you thought you did, could it have gotten changed in a scene recall?
Chris