Presumably an actual LCR system and not just LR + Front fills then? I only mention this as I have had both described each way around in a venue tech spec…
I also think Auxes are your only way to e.g. only feed the centre array on its own, as an LCR pan function would. I don’t think many people enjoy panning on Aux sends though outside of theatre workflows.
If your panning is relatively static throughout the show it makes everything easier. If it is practically mono for a lot of things, as many live mixes are, you could just send L+R post fader to a Matrix output for the Centre speaker/array. This isn’t LCR, it’s a centre-fill, but depending on the scale and layout of the venue, that might be precisely the intention. With a channel panned hard L, it will also come out C, and anything C will come out of all three etc.
You lose some point-source definition and potentially there is more phase interaction between speakers etc. but it’s probably not going to spoil your day.
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