ENGINE 3 SOFTWARE
Past Arctis 3 versions required you to download the Engine 3 software directly from SteelSeries, register the headset and get a code allowing you to use the software (mainly to enable surround sound and use the equalizer function) even via 3.5mm connectivity.
Still due to several audio related issues SteelSeries discontinued support for the Arctis 3 headsets from their Engine 3 software and instead makes use of the built-in spatial sound feature in Windows 10 (multichannel/surround audio).
This feature does work as SteelSeries describes but as mentioned above the Engine 3 software allowed end users to adjust many features/settings of the Arctis 3 headset, not just multichannel/surround audio (check here for more on that).