“According to the manual for my 828 I’m supposed to set my clock source to ADAT optical when importing tracks from my ADAT, however, I don’t see this option in the clock source dialog. What am I missing?”
You do need to set it for ADAT optical clock when transferring tracks. This is the only way the 828 has of resolving its clock to the ADAT, which is important to ensure a good transfer (much more about digital clocking issues is available in the inSync archives).
You’re on the right track. This setting is available in the clock source menu. The trick is that with the 828, the option to select ADAT optical does not appear in your clock source until you enable the optical INPUTS to either TosLink or ADAT. Enabling the outputs will not do it. Once you enable those inputs for optical, a 4th choice appears in your clock source box: “ADAT OPTICAL.”