The True Bypass Looper works with or without power. When you add a DC supply to this unit the two LED let you know if the loop is active or not. BLUE LED indicates your signal is passing through the vintage effect, RED LED indicates true-bypass. You can use it as a multiple effects switcher and add several effects in a chain and then switch them all on at once. You can also use it as a tuner mute switch. Plug a tuner in this box and not only prevent the tuner from draining away your tone, but tune in silence.