If you are hooking a soundbar or AV receiver up to a television, use HDMI ARC for most setups and optical audio when your gear is older, your cable run is long, or you are fighting electrical hum. HDMI ARC vs optical audio explained in one line: HDMI carries sound and control on the same cable you already use for video, while optical carries sound only, over a fibre strand, with no control channel at all.
Here is the part most comparison pages skip. The connector you pick matters far less than the formats your sources and your sound system can actually handle. Most television and streaming mixes are 48 kHz, and both connections usually move the exact same compressed bitstream from the TV to your speakers.
Table of Contents
- HDMI ARC vs Optical Audio at a Glance
- HDMI ARC vs Optical Audio: The Core Difference
- Sound Quality and Format Support
- Latency, Lip Sync, and Gaming
- Compatibility and Setup
- Which Should You Choose?
- Frequently Asked Questions
- Should I connect my soundbar via HDMI or optical audio?
- Is HDMI ARC or optical audio better for sound quality?
- Can I use HDMI ARC and optical at the same time?
- Can I use HDMI ARC just for audio?
- What if my TV does not have HDMI ARC or optical?
- Why is there no sound through my HDMI ARC connection?
- Conclusion: Start With Your TV and Sound System
HDMI ARC vs Optical Audio at a Glance
| Feature | Optical (TOSLINK) | HDMI ARC | HDMI eARC |
|---|---|---|---|
| Signal | Light through a fibre core | Electrical over copper HDMI | Electrical over copper HDMI |
| Carries video | No | Yes | Yes |
| Remote control / CEC | No | Yes | Yes |
| PCM stereo | Yes | Yes | Yes |
| Compressed 5.1 (Dolby Digital, DTS) | Yes | Yes | Yes |
| Dolby Digital Plus Atmos | No | Yes | Yes |
| Lossless Atmos (TrueHD, DTS-HD MA) | No | No | Yes |
| Audio bandwidth (reported) | Roughly 2 Mbps ceiling | Around 1 Mbps | Up to around 37 Mbps |
| Immune to electrical hum | Yes | No | No |
| Practical cable run | About 10 m | About 5 m | About 5 m |
Two things in that table decide most cases. Optical cannot carry Dolby Digital Plus Atmos, so any object-based mix from a streaming service gets flattened. And regular ARC has less audio bandwidth than optical in some reports, which sounds backwards until you remember ARC is often feeding a soundbar that decodes the bitstream itself.
HDMI ARC vs Optical Audio: The Core Difference
HDMI ARC stands for Audio Return Channel, and it arrived with HDMI 1.4 in 2009. It lets a television send audio back down the same HDMI cable that carries picture toward it, so one cable handles video going up and sound coming back, plus HDMI-CEC control commands that let your TV remote operate the soundbar.
Optical audio, called TOSLINK or S/PDIF, is a one-way digital link. The TV turns its audio signal into pulses of light, pushes them through a glass fibre core, and the sound system turns them back into digital data at the other end. No video, no control, and no power handshake. What it does have going for it is that light cannot pick up electrical interference.
A quick example. Watch Netflix on the TV, and the audio either travels back over the HDMI cable to the soundbar (ARC) or over the optical cable (S/PDIF). Plug a Blu-ray player into the soundbar directly and the TV is out of the loop entirely, so the connection type between TV and soundbar stops mattering for that disc.
Sound Quality and Format Support
Optical tops out at two channels of uncompressed PCM or a compressed 5.1 Dolby Digital or DTS bitstream. That is the hard ceiling, and it is why optical cannot carry Dolby Atmos in any form. Newer TVs sometimes advertise Atmos over optical, but what you actually receive is a Dolby Digital or DTS mix with the height channels folded in.
HDMI ARC handles compressed 5.1, plus Dolby Digital Plus Atmos from streaming apps, plus uncompressed PCM up to 5.1 channels. It does not carry Dolby TrueHD or DTS-HD Master Audio, which is why lossless Blu-ray Atmos usually drops to a lossy layer or gets blocked entirely.
HDMI eARC is where the ceiling lifts. It adds uncompressed PCM up to 7.1, Dolby TrueHD with Atmos, DTS-HD Master Audio, and DTS:X. The bandwidth figures quoted by third-party sources put regular ARC near 1 Mbps for the return channel and eARC up around 37 Mbps.
So does it actually sound different? For most people, on most content, no. Film and television mixes are delivered at 48 kHz, and both optical and ARC usually move an identical compressed stream from the TV to your speakers. Regular users on home theater forums consistently report that the audible gap between the two is small, with HDMI usually winning on convenience rather than on sound.
You will hear a real difference in three situations: a soundbar decoding Dolby Digital Plus Atmos over ARC versus a downmixed optical feed, a lossless Atmos disc over eARC versus no audio at all over ARC, and any comparison where one device is genuinely broken. Otherwise the deciding factor is your equipment’s decoding limits.
Latency, Lip Sync, and Gaming
Lip sync is where the two connections feel different in practice rather than in theory. HDMI is designed for audio and video to travel together, so receivers and soundbars apply automatic lip-sync correction and usually land close without you touching anything. Optical carries audio on its own path, so any correction is manual.
When dialogue lags behind lips on an optical run, look for an audio delay or lip-sync slider in your TV’s sound menu first, then in the receiver. Common values run from about 20 ms to 200 ms. Start low and step upward in 10 ms increments while watching something with clear mouth movement.
Gaming adds its own wrinkle. Many televisions apply picture processing in game mode that adds a small amount of delay, and some TVs delay their audio output to match. If you are connecting a console directly to the sound system, neither connection is involved in that path at all.
If you are routing console audio back through the television over ARC, expect the television’s processing to sit in the way. For competitive play, connecting the console straight to the soundbar or receiver, and the TV to the sound system for everything else, gives you the cleanest timing. Optical does the same job here, just without the control features.
Compatibility and Setup
Start by identifying your ports. On most televisions, the ARC port is an HDMI input labelled ARC, eARC, or with an asterisk, and it is often input 2 or 3. On a soundbar, you want the port labelled eARC, ARC, or TV OUT, which is the one that sends sound back to the television. Soundbars with only one HDMI socket cannot accept a console at the same time, because that single port is doing double duty.
Optical output, when present, is a square-shaped port labelled Optical, S/PDIF, or TOSLINK. Plugging into the wrong one of these is the single most common reason people report no sound over HDMI ARC.
One behaviour surprises people: a TV’s optical output usually does not pass through the full surround mix that arrived over HDMI. It decodes to what its own DAC supports and re-encodes, which often means a stereo or 5.1 downmix. That is a TV limitation, not a cable fault.
CEC control works differently by brand. Samsung calls it Anynet+, LG uses SimpLink, Sony uses BRAVIA Sync, and Panasonic uses Viera Link. Turn it on in the TV’s settings menu, not just the soundbar. If the soundbar changes inputs on its own or the two volume controls fight each other, that is CEC misbehaving, and turning it off on one device usually fixes it.
For eARC, cable certification matters more than people expect. You need a cable labelled High Speed with Ethernet, or an Ultra High Speed cable. A basic high-speed HDMI cable can silently disable eARC features, which is a common source of frustration when a setup works with someone else’s cable and not your own.
If you want to run both at the same time, you can. Connect HDMI ARC to the soundbar and optical to a separate amplifier or powered speakers. The TV’s optical output and its ARC return are independent, so both can play at once from different devices.
When audio goes missing, work through it in order: confirm the TV input is set to the right HDMI port, confirm ARC is enabled in the TV’s HDMI-CEC settings, confirm the soundbar input is set to TV rather than HDMI 1, and try a known-good cable. On TVs with several HDMI ports, HDMI 2 and 3 are sometimes the only ones wired for return audio.
Which Should You Choose?
Use HDMI ARC when you have a modern television and soundbar or receiver and you want one cable and one remote. It handles streaming Atmos, auto lip sync, and power-on control without extra setup. Choose eARC instead whenever your gear supports it, since it is the only one of the three that carries lossless Atmos.
Use optical audio when your receiver predates HDMI 1.4 and has no ARC at all, when you are running cable through a wall or across a room longer than about 5 m, or when you hear a low hum that comes and goes with other equipment switching on. Optical is the standard fix for ground-loop hum because light cannot carry the electrical loop.
Use optical when HDMI control misbehaves and you would rather manage inputs yourself. Some people actively prefer a setup where the soundbar does not react to the TV remote at all, because it stops the soundbar waking up during a late-night gaming session.
Use both when your system has a receiver for the main speakers plus a set of powered speakers elsewhere. There is no rule against running the two paths in parallel, and in a multi-room house it is usually the simplest wiring.
Frequently Asked Questions
Should I connect my soundbar via HDMI or optical audio?
Use HDMI ARC for a modern soundbar and television. It carries compressed Dolby Digital Plus Atmos, gives you automatic lip sync, and lets the TV remote control the soundbar over one cable. Pick optical only for older receivers with no ARC, long cable runs beyond about 5 m, or setups where HDMI control causes conflicts or electrical hum.
Is HDMI ARC or optical audio better for sound quality?
For most film and television content, the difference is small or inaudible, because TV and streaming mixes arrive at 48 kHz and both connections move the same compressed bitstream. You will notice a real difference with lossless Dolby Atmos or DTS:X over eARC, or when comparing a downmixed optical feed against a Dolby Digital Plus Atmos feed. Equipment decoding limits matter more than the connector.
Can I use HDMI ARC and optical at the same time?
Yes. A television’s optical output and its ARC audio return are independent, so you can send sound to a soundbar over HDMI ARC while feeding a separate amplifier or powered speakers over optical. You choose which input to listen to, and some setups even play both at once. Nothing about HDMI ARC disables the optical output.
Can I use HDMI ARC just for audio?
You can, but you still need the HDMI cable plugged into an HDMI port. Audio Return Channel simply reserves part of that cable’s bandwidth to send sound back to the soundbar while video continues flowing the other way. If nothing is plugged into another HDMI port on the TV, ARC still works normally and you simply get audio with no picture.
What if my TV does not have HDMI ARC or optical?
Check for HDMI-CEC on any HDMI port first, since some older sets support control without a dedicated ARC label, though bandwidth will be limited. If there is no optical output, your options are a coaxial digital out, an RCA analog stereo pair, Bluetooth, or streaming audio from the TV’s own apps. A soundbar with its own HDMI input and a device with a direct output is often the cleanest workaround.
Why is there no sound through my HDMI ARC connection?
Confirm the TV input is set to the HDMI port labelled ARC or eARC, that HDMI-CEC is switched on in the TV’s settings menu, and that the soundbar input is set to TV rather than HDMI 1 or 2. On many televisions only HDMI 2 and HDMI 3 support audio return. If eARC features are missing, try a cable labelled High Speed with Ethernet or Ultra High Speed.
Conclusion: Start With Your TV and Sound System
Check the port labels on your television and soundbar first, then pick the connection that matches the formats you care about and the gear you already own. HDMI ARC, or eARC where it exists, wins for almost every modern living room. Optical stays the sensible fallback for older receivers, long in-wall runs, and hum you would rather not troubleshoot.
