The 888 Audio Interface only accepts a Sample Rate clock on AES inputs 1/2, which means that the DAT Machine (or other stereo digital source) must be connected to AES inputs 1/2.The other AES inputs on the 888 can be used as effects returns for processors with digital I/O, or with a device that has multiple AES outputs (the AES pair providing the Sample Rate clock must still be connected to inputs 1/2 on the 888).