The power supply is optional (We sell them for $25). It's an option because most people power with a Pedal Power. The PP2+ will power the PBC if you use a current doubler cable with outputs 5 and 6. The PP Iso 5, Digital, 4x4 and Mondo will all power the PBC using one of their 12VDC 400mA outputs. Also, the Pedal Power is quieter than any wall-wart we can buy.