Elizabeth, an example of my reference to "reduced sensitivity to cable effects and differences (particularly if the output impedance of the component driving the cable is low)," and note that I did not say NO sensitivity, I said "reduced sensitivity," would be the ground-loop induced high frequency noise, and consequent degradation of background blackness, that I referred to. And ground-loop induced hum, as well.
With an unbalanced interface, the severity of those effects will be directly proportional to the resistance of the cable shield, or other return conductor if the return conductor is not the shield. That resistance, which is usually not specified, will differ unpredictably for different cables. With a balanced interface, differences in that resistance will not matter, or will matter very little, because the receiving circuit is essentially responding just to the difference between signal line voltages, not to the difference between signal and return line voltages (the return line being what is sensitive to ground-loop effects, because it is normally common with both chassis and AC safety ground).
Also, you may have seen in the past several comments by no less an authority than Atmasphere, making the following two points:
1)A balanced driver circuit that has low output impedance, and is capable of driving low impedance loads (specifically 600 ohms) without signal degradation, will result in there being NO sonic differences between the balanced cables that may be used to connect that output circuit to the destination component.
2)Many and probably most balanced driver circuits are not designed with that capability, and hence will not provide that benefit to the degree that it should be provided.
Finally, I can recall seeing more than a few threads here in the past in which people indicated that in their experiences balanced interfaces seemed less sensitive to cable differences than unbalanced interfaces.
Regards,
-- Al
