The HDMI ARC port on your TV has a very specific job - Engadget

"HDMI ARC or HDMI Audio Return Channel was introduced into the HDMI specification (in this case HDMI 1.4) in 2009 with a specific purpose: simplifying and improving the experience of getting audio from your TV to a speaker. Historically, soundbars and other audio equipment have used optical cables to transfer digital audio, which meant introducing yet another cable to your TV or routing everything through a dedicated, expensive home theater receiver. ARC lets an HDMI port do the heavy lifting, eliminating the need for a separate audio cable and giving you access to the sort of high-quality audio that was previously locked behind specialized equipment."

"TVs offer more than just one type of HDMI port, however, and many specifically include HDMI ARC and HDMI eARC, versions of the interface that support soundbars for higher-quality audio. The distinction between various flavors of HDMI can get a bit technical, but if you can understand the difference, it's possible to unlock improvements like more immersive audio from Dolby Atmos just by plugging in the right cable into the right port."

"While some soundbars, such as Sonos' Beam and Arc Ultra, default to HDMI ARC or HDMI eARC connections to offer crisper, more immersive audio, that doesn't mean you have to switch. If you're happy with what you get from your TV's built-in speakers, a soundbar might not be for you at all. And if you already have a soundbar that only offers optical audio out (also known as a TOSLINK port), the vast majority of TVs made today still offer that connection."

"The only disadvantage is that optical audio cables can't handle as much data as HDMI cables."

HDMI connects devices like game consoles and streaming boxes to TVs, but TVs may include different HDMI types. HDMI ARC (Audio Return Channel) was added to the HDMI specification in 2009 to simplify sending audio from a TV to a speaker. ARC reduces the need for separate optical audio cables by allowing an HDMI port to carry audio back to compatible audio equipment. Many soundbars use HDMI ARC or HDMI eARC for higher-quality audio, including Dolby Atmos support when connected correctly. Optical audio (TOSLINK) can still be used on most modern TVs, including with soundbars that only provide optical output. Optical audio cannot carry as much data as HDMI cables.

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