I was working at a fair and there was a local dance group that showed up without any audio equipment. I understand not bringing a PA, but they didn’t bring an adapter to get their phone’s music to the PA. That’s literally a $10 part that’s super tiny and easy to travel with. Because they didn’t have that, they had to do this for their music:
It sounded like garbage and when the dance group is trying to get new students as part of their show, it doesn’t look good.
Personally I travel with all the XLR cords and adapters I need to plug into a standard sound system. Sure there’s the odd time when I run into an unusual sound system that’s really a consumer (back yard) type of speaker and not intended for professional live sound. Those will typically run on 1/4 or 1/8 inch plugs, which I usually have as well.
I should mention that I did have the adapter that they needed, but didn’t let them use mine. I’m not mean, but the first and last time I let a dance group use mine, they took it! That then affected my ability to do my show by helping them do their show. I’ll never let anyone I don’t know borrow things that I need to do my show.
The moral of the story is that if a $10 part is why your show sounds like crap, buy that and carry it with you.
-Louie