Optical audio output is used to link Macs to home theater setups and A/V systems capable of multi-channel surround sound, by way of a mini TOSlink adapter connected to the 3.5mm jack.

In the 2015, and earlier, MacBook Pro, and every other Mac model with optical audio out on the 3.5mm jack, the listing is amplified with a statement like "support for audio line out (digital/analog)." ...

Jeff K. has a bone to pick with Apple: I have a great set of speakers that I connected to my old iMac with a optical audio/mini-plug cable through the headphone jack. They had terrific sound ...