Re: Festival Goers/Campers: Solar solution for music?
get one of those jumpboxes from an auto parts store, or the auto section at walmart. You can charge it via electrical outlet before you leave. Most of them have usb ports now, as well as sockets for wall warts, so you could run anything for a while. Bonus, if your car battery dies, you can jump it.
And some are made so you can charge them from a car battery as well as an electrical outlet so you might be able to get one you can charge on the spot if you use it up. Theres a bunch of different kinds with various options.