hoyt,
as the story goes, AES was designed to use the typical standard mic cable of the day, only a bit more tightly specified. Nowadays, mic cables comes in all kinds of shapes so you cannot really be sure what impedance they are. My suggestion is that you get the special 110 Ohm digital AES cable, better safe than sorry. An advantage of that cable is that it can be used as a mic cable withouth problems if the need arises. If you select to use normal mic cables, don´t add any resistors or anything like that, simply use quality stuff wihtout any additions.
Gunnar