Is Optical Audio Better Than HDMI? It Depends on the Format
Quick Answer: For sound quality, no: HDMI ARC and eARC carry more formats, including Dolby Atmos and lossless multichannel, while optical TOSLINK is limited to compressed 5.1. Optical wins on electrical isolation and on compatibility with older equipment.
Both cables move digital audio from a television to a sound system. The difference is bandwidth, and bandwidth decides which formats survive the trip.
Bandwidth Sets the Ceiling
TOSLINK over plastic optical fiber carries a limited data rate, which is enough for stereo PCM and for compressed 5.1 bitstreams. It cannot carry the higher-rate streams that modern formats use.
What optical carries
Two-channel PCM, Dolby Digital 5.1 and DTS 5.1 are the practical ceiling. That covers most broadcast television and many streaming apps.
What HDMI adds
HDMI ARC carries the same compressed formats plus a control channel. eARC raises the bandwidth enough for Dolby TrueHD, DTS-HD Master Audio and object-based formats such as Atmos.
Formats Side by Side
The table describes what each link can deliver to a soundbar or receiver, assuming both ends support the format.
| Format | Optical TOSLINK | HDMI ARC | HDMI eARC |
|---|---|---|---|
| Stereo PCM | Yes | Yes | Yes |
| Dolby Digital 5.1 | Yes | Yes | Yes |
| DTS 5.1 | Yes | Yes | Yes |
| Dolby Atmos | No | Compressed only | Yes |
| TrueHD / DTS-HD MA | No | No | Yes |
| CEC control | No | Yes | Yes |
Where Optical Is the Better Cable
Optical has two real advantages that have nothing to do with format support.
Electrical isolation
Light does not carry ground. When the television and the amplifier sit on different circuits, or when a hum appears only with the cable connected, optical breaks the loop.
Compatibility with older gear
Every television from the last two decades has an optical output. Older receivers and soundbars often have optical and no HDMI, which makes it the only digital path available.
Where HDMI Wins
If both devices support eARC and the content uses lossless or object-based audio, HDMI is the only path that preserves it. HDMI also carries CEC, so one remote can control volume and power.
The cable requirement
ARC works over a standard High Speed cable. eARC needs Ethernet-capable conductors and, for the highest rates, a certified Premium or Ultra High Speed assembly.
Handshake and switching
ARC depends on a successful handshake and on the correct input being selected. When it misbehaves, the usual causes are CEC settings and an incompatible splitter in the chain.
A Practical Decision
Use eARC when the sound system supports it and the content carries object-based audio. Use optical when the equipment predates HDMI audio, when hum is a problem, or when the television’s ARC implementation is unreliable. Both cables are inexpensive; the decision is about formats and isolation, not about which one is more modern.
Two Living Room Setups
The cable choice follows from the sound system, not from the television alone.
A soundbar with eARC and a 4K television
eARC carries Dolby Atmos and lossless audio from the television’s apps. A certified High Speed or Premium High Speed cable is enough for the audio path.
An older receiver with a persistent hum
The hum disappears when the optical cable is connected and the HDMI audio path is removed. Optical breaks the ground loop between the television and the amplifier.
A projector where audio returns over HDMI only
Some projectors pass audio back through ARC but not through an optical output. In that room the HDMI cable is the only path, so the receiver must support the same formats and the cable must carry the return channel. Optical remains the fallback if the ARC handshake fails.
Frequently Asked Questions
Is optical audio better than HDMI for sound quality?
No. Optical is limited to compressed 5.1, while eARC carries lossless and object-based formats. Optical can sound identical when the source is a broadcast stereo or Dolby Digital stream.
Can optical carry Dolby Atmos?
Not in its lossless form. TOSLINK lacks the bandwidth, so Atmos over optical is limited to compressed implementations and is uncommon.
Why does my soundbar only work with an optical cable?
The television’s HDMI port may not support ARC, or CEC may be disabled. Optical works independently of the HDMI control channel.
Does optical cable quality matter?
Less than for copper at these rates. A undamaged plastic fiber with clean ends works; sharp bends and dirty connectors are the usual causes of dropouts.
Can I use both optical and HDMI at the same time?
You can connect both, but the television outputs to one path at a time. Running both is useful for testing, not for simultaneous audio.
How this guide was built: Built from digital audio interface practice: TOSLINK bandwidth limits, ARC and eARC payloads, and ground-loop isolation. Disclosure: No manufacturer names or prices are given. Format support depends on both devices; confirm the supported codecs in the manuals.