Do you mean turning it on before turning on the sound bar? When I have them connected on HDMI/ARC the sound bar turns on automatically after I turn on the TV. I did turn off the HDMI CEC as you suggested which leaves only optical available besides TV speakers. So I unplugged everything including power, then powered them and turned them on. Then hooked them up with optical, played a movie from Amazon (in Dolby), the bar and subs worked, but no sound from the side and back speakers.