There's hardly anything that will effect my performance more than the sound system and the people operating it. Collectively, they can make me sound like a million bucks or make me sound absolutely horrible. It can effect things like sales at the merchant table, the enjoyment of the experience by the audience and musicians, as well as more serious things such as if someone will ever come back to hear me again or not. For sometimes, an audience member might not be aware that music can be irritating, or worse, because of poor handling of the sound reinforcement and they react to this subliminal experience. I've recently had a few frustrating dates with poor sound at an otherwise well organized event.
I'm going to have to add a sound person to my bill, someone that will do every show with me, as I did when I performed regularly with the Pancakes. It doesn't matter if presenters think this is demanding or problematic, it's a matter of making sure the audience is not shortchanged. Additionally, there is usually a correlation between how good the sound is and how many CDs I sell at the event.