i'm with charlie, if the board outputs AES on XLR definately go that route if the 744 has a digi on XLR input. (i run a korg MR1k, so no 744 in da house to look at).
if you can only get digi out on xlr and have only digi on co-ax in, most decks will accept the xlr signal in an unbalanced format (sonys most often don't like it imh_experience). s/pdif co-ax is 1v peak-peak, aes is 5v p-p.
so a cable with XLR pin 2 hot (RCA center pin) and pin 1 and 3 tied to ground (RCA shield) usually works. the CORRECT solution is to use a transformer to convert from balanced digi to unbalanced digi as the cable impedance and voltages between the two standards are different.
remember aes digi does have differences in subcode data when compared to s/pdif but should really matter in this case at all.
nism