i am trying to use an audio magic excalibur II digital xlr cable to run from a mytek to the 744, but the 744 will not pick up the signal??? so i tried another digital xlr cable (tara labs) that i have and it worked fine. so then i tried the tara labs cable out of the mytek then plugged the audio magic cable into the tara labs and ran it into the 744, and it works fine?? anyone know why in the world this might happen?? also can someone tell me what makes an xlr cable digital vs. analog??