Digital optical cables, commonly known as TOSLINK, transmit digital audio as pulses of light through a fibre optic cable rather than as an electrical signal through copper. This gives optical cables one genuine advantage over their coaxial counterparts: complete immunity to electrical interference and ground loop hum, since there's no electrical connection between the two connected devices at all.

This makes optical cables a particularly practical choice when connecting equipment that might otherwise be susceptible to ground loop noise, or in setups with a lot of nearby electrical equipment. Optical connections are commonly found on TVs, AV receivers, games consoles and DACs, offering a straightforward audio-only digital connection alongside or instead of HDMI. It's worth noting that optical cables are generally more limited in bandwidth than HDMI or coaxial connections, and can be more delicate, since sharp bends can damage the internal fibre.

For a genuinely interference-free digital audio connection, particularly in setups prone to electrical noise, a digital optical cable offers a dependable and widely compatible solution.