This is not just a headphone socket. It's also an optical S/PDIF connection, which you can use with a Mini-TOSLINK to TOSLINK cable to connect your Mac to your Hi-Fi‡.
Sadly, without Aura, you get 2 channel stereo†.
With Aura, you get full 5.1 surround sound*.
‡ if you have a machine from 2016 or later, it may not have an optical connection — check the Apple Tech Specs website if you're unsure (it should list digital or optical output under the 3.5mm audio jack); machines without built-in S/PDIF may work with a USB audio adapter
† except for pre-encoded content, in applications with special support (e.g. DVD Player)
* requires a Dolby® Digital™ compatible A/V receiver or surround amplifier with a TOSLINK optical input; not all applications support multichannel audio