The only reason I could see wanting to use a battery pack would be if the person was playing in an area like a subway station, etc where there wasn’t easily accessible power. Otherwise it’s such a bad idea to be relying on a battery. Especially if people are daisy chaining their effects to some random battery they got on amazon for cheap. Better to just use the adaptor with actual power. People love to over complicate their setups for no reason, and then rely on a battery they got for 30 bucks