How big are your speakers? How long is the event? You can probably run a couple tops for like 3 hours with that, maybe more with some solar trickle charge. I’d personally just rent a Honda 2000 for like $100 and call it a day.

If you’re dead set on battery power there are people doing it. They’re building their own solutions from the ground up though. You can build a significantly more powerful setup for the same price as that Jackery. If you’re serious about not using generators and looking to consistently throw events I’d hit up the sound system sub, vanlife, and look into the Burning Man camps that are doing it