I hooked up my H7600 to a Tascam DM4800 digital mixer via AES/EBU digital cables. I then send the signal back and forth to my digi 002R via the ADAT light pipe. I use my mixer as the master clock for both my 002R and the H7600, running everything at 48Khz. I do not have any digital clock issues whatsover. On that basis, I assume the firewire might do somehting, but I'm not sure if the 003 can use the firewire as an input mehtod. it's typically used to communicate between the 002/003 and the host computer's CPU. I know for a fact that the firewire in my 002R is totally useless as a signal I/O, not emant for that. Only digital I/O is 8 channels of ADAT and stereo SPDIF, no AES/EBU unfortunately.