I don't think what you want to do is possible with those particular devices. Neither of those units are designed to output their analog input via ADAT. They can send and receive output from devices that do convert analog input to ADAT. You could use a Behringer ADA8000, Presonus Digimax or the like to get 8 more channels via ADAT into either of those but the 003 or Saffire won't do that.