Digital audio travels as data, not as sound, and somewhere along the way it has to be converted back into the analog signal a speaker can play. The cable in that chain is the digital audio cable, and the component that does the conversion is a DAC. Understanding where each sits explains most digital-audio connection questions.
Digital to Audio Cable: Optical, Coaxial and the DAC in Between
Quick Answer / Summary: A digital to audio cable carries a digital audio signal, most often over optical (TOSLINK) or 75-ohm coaxial cable, to a digital-to-analog converter (DAC) that turns the digital data into the analog signal speakers play. The cable itself does not convert; the DAC does.
What Digital Audio Is
Digital audio represents sound as a stream of numbers sampled at a fixed rate, such as 44.1 or 48 kilohertz, at a fixed bit depth. That stream is what travels down a digital audio cable, either as pulses of light or as an electrical signal.
Numbers, not sound
Because it is data, a digital cable either delivers the bits or it does not. There is no gradual hum or signal loss like analog, but a failing digital cable can produce clicks, dropouts or silence when the receiving device cannot reconstruct the clock and data.
The key point is that a digital audio cable never touches the actual sound. It moves numbers to a converter, and the quality of that converter, more than the cable, decides what the final analog signal sounds like.
Optical and Coaxial Digital Cables
Optical, or TOSLINK, carries digital audio as light through a fiber strand. It is immune to electrical interference and ground loops, and it appears on TVs, soundbars, game consoles and receivers as a square port.
Light versus electrical
Digital coaxial uses an RCA-style connector on a 75-ohm cable to send the same digital audio as an electrical signal. It is just as capable as optical for common formats, but it needs a proper 75-ohm cable to avoid reflection and errors.
Both carry up to 5.1-channel compressed audio or 2-channel PCM. For higher-bandwidth formats such as Dolby Atmos, HDMI ARC and eARC have replaced both, since HDMI carries more channels and adds control.
Where the DAC Lives
Every device that plays digital audio has a DAC somewhere. In a soundbar, receiver or powered speaker, the DAC is built in, so the digital cable feeds the device directly and the device converts and amplifies.
A standalone DAC is used when the built-in converter is poor or when connecting digital sources to a system without a digital input. The digital cable runs from the source to the external DAC, and an analog cable runs from the DAC to the amplifier.
So a ‘digital to audio’ setup is usually a source, a digital cable, a DAC and an analog cable. The DAC is the translator, and its position in the chain is what most people are actually asking about when they search for a digital to audio cable.
Choosing a Digital Audio Cable
Match the cable to the ports on both devices. If both have optical ports, use a TOSLINK cable; if both have coaxial digital ports, use a 75-ohm coaxial cable. A converter is only needed when the two devices use different connector types.
For optical, handle the fiber carefully and avoid sharp bends, which can crack the strand and cause dropouts. For coaxial, buy cable labeled 75-ohm rather than an ordinary audio RCA cable, because impedance matters for the digital signal.
Keep the run reasonable and the connections clean. A digital cable that clicks or drops out is usually a damaged connector or a kinked fiber, so inspect both ends before replacing the rest of the system.
Optical vs Coaxial Digital Audio
| Attribute | Optical (TOSLINK) | Coaxial Digital |
|---|---|---|
| Signal | Light pulses | Electrical |
| Cable | Fiber strand | 75-ohm coaxial |
| Interference | Immune | Susceptible to hum |
| Max format | 5.1 compressed / 2-ch PCM | 5.1 compressed / 2-ch PCM |
| Best for | Noisy environments | Short, clean runs |
Real-World Application Scenarios
A user connects a TV’s optical output to a soundbar’s optical input with a TOSLINK cable and sets the TV to PCM; another runs a 75-ohm coaxial cable from a CD transport to a standalone DAC, then analog RCA from the DAC to the amplifier; a third adds a converter because the source has optical but the receiver has only coaxial.
Recommended Internal Resources
See stereo optical cable for TOSLINK basics and fiber optic sound cable for the optical path.
Frequently Asked Questions
What is a digital to audio cable?
It is a digital audio cable, usually optical or coaxial, that carries the digital signal from a source to a DAC, where the digital data is converted into the analog audio that speakers play.
Is optical better than coaxial for digital audio?
Both carry the same common formats. Optical is immune to electrical noise and ground loops, while coaxial needs a 75-ohm cable but works identically in a clean, short setup.
Do I need a DAC if my receiver has optical input?
No, the receiver has a built-in DAC. A standalone DAC is only needed when the built-in converter is poor or the amplifier lacks a digital input.
Why does my digital audio cable cut out?
Dropouts usually come from a damaged or kinked fiber, a loose connector, or a failing 75-ohm cable. Inspect and reseat both ends before replacing components.