@SteffenR

Or maybe we know more than you think we do.

We definitely need EQ for each of our channels.

Although I do with the dealer had done the output LR first by ringing out the room.
We still do have some special cases of standing waves that need that ONE mike EQd to stop feedback.

Discovered that when a show used our facility and some kid raised a mike as they all did because of different heights of kids
and then suddenly FEEDBACK. That mike was exactly at the spot our tall pastor talked from when we had problems with HIS Mike.

The problem was not the usual stuff but is clearly a standing wave that hits at that one point.
And yes, the MD is looking at further treating of the apse to help stop reflections more.
We already adjusted the inside window shutters to bounce sound down into the rugs and audience instead of up into the ceiling and walls. And we added hanging cloth items along the walls to also help some. Next is paying to treat the back wall to finish the job.