Many players have different opinions on whether to use batteries or a power supply for pedals. The battery camp says that as the battery drains and the voltage drops there’s a certain tone their pedals get. The power supply camp says that batteries become expensive and some power supplies have a “battery simulator” built in so you can dial in a lower voltage and current to simulate the sound of a partially drained battery. Both sides have valid points. There is actually a third camp that use both. Why? Practical reasons only. In an emergency situation if your power supply stops working your pedals are already loaded with batteries so you can get through the gig without a hitch. This is sort of like a “spare tire”. It pays to be covered so you can concentrate on playing your best and reduce any unecessary stress.