The only Roku-based ONN Soundbar is the Smart Soundbar, and it has both an HDMI ARC port and an Optical port for audio input (you hook up the either the HDMI ARC port from/to the TV, or the Optical port from the TV (or DVD player)).
ARC (Audio Return Channel) sends audio from the TV back to the audio device, while the video travels from the audio device to the TV (requires that both the HDMI port on the TV and on the audio device be ARC enabled/labelled).
ARC is preferred to Optical since it carries more/higher quality audio formats (and requires less cables).
However, if your TV doesnt support ARC, you'll need to use the Optical cable from the TV (or DVD player) if you want audio from the TV/DVD player.
