If you need a reliable source of power for your pedals that maintains sound quality and allows you to use your pedal to its full capacity, you’re going to need a power supply. When it comes to powering many pedals, 9V batteries are extremely unreliable and should be used sparingly.
A power supply puts the correct voltage through your pedal at all times and as long as there is a supply of power coming through the mains, it won’t let you down on stage. Plus, unlike 9 Volt batteries, you can leave your pedals plugged in and it won’t sap any power.
A pedal power supply also saves time as it’s a simple plug in and play job, and it cleans up your board as adapters plugged into a four-way tends to get a bit messy after a while. You switch it on and they just work – simples.