I just got a new 2020 iMac (i9) and I have an old Logitech sound system I used to connect to my old Mac Pro via optical digital audio cable. The Logitech system only accepts digital audio input (optical or coaxial). I want to hook my iMac to it but have no idea how to go about it except via USB. I value the community here and would appreciate your suggestions. I know that the headphone jack no longer carries digital output (since 2017?) Suggestions?