What is an ADAT interface?
What is ADAT? ADAT is an optical audio protocol designed to transfer digital audio to and from two audio devices. At 44.1/48kHz sample rates, ADAT can transport 8 channels of uncompressed digital audio to and from an interface and peripheral device with just one Toslink cable.
How do I add more outputs to my audio interface?
Click the little + sign in the lower left corner; an Aggregate Device box appears, and you'll see a list of available I/O. Check the interfaces you want to aggregate, and check “resample” for the secondary interface or interfaces. Now all input and output options will be available in your host program.