After reading so much about using USB out I tested this over the weekend. My preference was optical over USB. The difference was noticeable to my ear. Source is mac mini to a PS Audio DLIII dac. The USB was run straight in to the dac while the optical is fed to a Monarchy Audio Super DIP with coax out to the dac. Before listening I optimized the mac's digital out for each cable.
I have been using the optical out for about a year now and am happy with it.
I have been using the optical out for about a year now and am happy with it.