yes, there are. you're right--there are plenty who would say balanced lines sound better. and perhaps they are right too.... in fact, i am SURE they believe that it does sound better........
however, for most designs, balancing the signal should result in a degredation of fidelity, not an increase. the benefits come from noise rejection, which could otherwise be very loud in long cable runs. otherwise, you are adding more stages in the signal path, and virtually doubling the amount of wire used in the cable.
anyway.... arguing about this is pretty much like arguing that certain cables sound better. i will tell you, balanced cables are inheritently less "pure" than unbalanced lines. that is a FACT (at least for all but the most extravagant of designs.) just like it's a fact that vinyl is vastly lower fedelity than the CD, at least in any measurable terms..... and i's also a fact that frequency response among cables is practically immeasurable............
but that does not mean that one will not "hear" a pleasurable difference.
but anyway.... just letting you know.
i would like to just point out briefly that there are many high-end cables that do not even have shielding: Kimber, Nordost, etc.... so, you can see what many people think about the need for extra noise rejection....
