In this guide
TOSLINK carries audio via light pulses through a fiber optic cable, while digital coax carries audio as electrical signals through a copper cable — both transmit digital audio, but coax supports higher bandwidth and TOSLINK is immune to electrical interference.
- Your devices have matching TOSLINK or coax ports
- You’re sending stereo PCM, Dolby Digital, or DTS
- TOSLINK: running cable through a noisy or long path
- Coax: using a short, well-shielded cable run
- You need Dolby TrueHD, DTS-HD MA, or Atmos — neither supports these
- TOSLINK is bent sharply — fiber strands break and signal fails
- Coax cable runs long distances near RFI sources — quality degrades
How Each Connection Works
TOSLINK (also called optical audio) uses a squared connector and transmits audio as pulses of light through a fiber optic cable. Because it uses light rather than electricity, it is completely immune to electrical noise and ground loop hum.
Digital coaxial audio uses an RCA-style connector — often orange — and transmits audio as an electrical signal through a copper wire. It behaves similarly to a standard RCA cable but is designed with 75-ohm impedance for clean digital signal transfer.
Audio Quality and Bandwidth
For everyday listening, both connections sound identical when used correctly. The real differences show up at the limits of each format.
| Setup | Works? | Need | Note |
|---|---|---|---|
| Stereo PCM (CD/DVD) | Yes | Either cable | Both handle this easily |
| 24-bit/192kHz PCM | Coax only | Coax cable | TOSLINK tops out at 96kHz |
| Dolby Digital / DTS | Yes | Either cable | Standard surround formats pass through fine |
| Dolby TrueHD / DTS-HD MA / Atmos | No | HDMI ARC/eARC | Neither coax nor TOSLINK has enough bandwidth |
Coax supports uncompressed PCM up to 24-bit/192kHz. TOSLINK is limited to 96kHz, which is enough for most sources but rules it out for high-resolution audio files at the highest sample rates.
For a deeper breakdown of how digital audio travels over different connection types, What Hi-Fi’s guide to coaxial vs optical vs HDMI is a thorough reference.
When to Choose TOSLINK
- Your setup has electrical noise or ground loop hum
- The cable needs to run near power cables or other interference sources
- You only need stereo PCM, Dolby Digital, or DTS 5.1
If you’re connecting devices that also handle video signals, you may find our article on whether USB-C can connect to HDMI useful for understanding audio-video routing over modern ports.
When to Choose Coax
- You want the highest possible PCM bandwidth (up to 192kHz)
- The cable run is short and shielded from interference
- Your source or receiver lacks a TOSLINK port
Keep in mind that neither coax nor TOSLINK can pass lossless surround formats. If your AV receiver supports Dolby TrueHD or Atmos, you’ll need HDMI. Readers dealing with video handshake issues may also want to check why USB-C to HDMI connections sometimes fail, since similar signal compatibility rules apply.
Bottom line: Choose TOSLINK when noise isolation matters or cable routing is awkward. Choose coax when you need maximum PCM bandwidth and a clean short run. For lossless surround sound formats, skip both and use HDMI ARC or eARC instead.