Hi
It does rather depend on the venue and your sound source.
The problem with a real stereo image is that the customers dancing, or sitting to one side tend to only get half of the sound unless its panned to the centre or very near.
Especially if you are using a wide stereo source image and wide speaker placement.

Therefore central panned stereo or mono via two speakers / channels would be more suitable . and share the sound out better and make it perceptibly louder.
The Yamaha stage pass works this way as each speaker and channel is 300 watts hence the name 600 .
It has different input arrangement into the inbuilt mixer and at least two of them can take a stereo signal in and send a mono mix, of say a stereo keyboard to both speaker outs
I had a Stage pass 300
Here are some pics may help.

Mike

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BIAB2021 UltraPlus,AsusN55S1Tbssd, W10/64,Akai EIEpro
Yamaha CVP405,SquireStrat, CoolsoftVMidSynth
Novatation Impulse61 Ctr kbd, Cwalk blab Kontakt

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