The previous generation of iMacs had optical digital out through the headphone jack. This was one thing I had to have when purchasing a new computer. Apparently Apple decided to remove this feature on the 2017 iMacs. Does anyone know if it's possible to connect 5.1 speakers through some sort of adaptor or something? Here is where I found out that optical out is no longer supported.
https://support.apple.com/en-us/HT204392
https://support.apple.com/en-us/HT204392