I have done a few shows.

Be very careful the promoters know if you have a high current need. Tell them what you will be running and the current draw. Current draw should be posted somewhere on any machines your taking.

Put it in writing and have them acknowledge it when you pay.

One rather large outdoor show that I have done has the worst electrical setup ever. There will be one receptacle with 15 extension cords hooked up through power strips. The promoters guaranteed 20 amp circuits to everyone. The circuit breakers tripped more times than I could count.

If you can't run your equipment there is no way to make money.