XPND 1: Standard power supplies will not fit under the smaller XPND 1 pedalboard. For XPND 1, a standard power supply would need to be mounted on top. Alternatively, many players choose to use a daisy chain power supply with XPND 1.
XPND 2: The underside of XPND 2 can fit most standard power supplies. A power supply can be mounted underneath to the non-expanding side.