I will try to make this simple explanation:
MacPro has an optical audio IN/OUT
get an TOSLINK optical cable like this https://bit.ly/2tSzE3
connect one end to the MacPro’s optical audio IN to the 828’s optical audio OUT
On your DAW (audio editing software) you must choose the optical input as the source
This can also be set in System Preferences so that even Garageband will automatically use this as the connection for inputs.
– Internet Marketing, SEO, PPC @ TrapikMedia.com
– Audio Engineering and Music Production @ Sound-Weavers.com