The new 2.5 updates for the EP-133 KO II and EP-40 Riddim and the 1.5 update to the EP-1320 add USB audio interface and other features.
If you want to use an EP unit to receive input audio over USB (possibly to use as a send effect) you need to change a system setting.
Press [Shift] + [System], then navigate to the last page SMP > USB and set to MON.
If you don’t already hear your USB source, press [Main] and turn up the X knob to increase input level.