01-26-15: Pkoegz
If someone sees flaws or can articulate it better please do.
Here's my take:
Single-ended by definition means the same thing as unbalanced. So a single-ended cable or connection cannot be balanced.
It is possible for a balanced connection to be implemented via RCA connectors, but that is not usually done.
A balanced cable will have two symmetrical conductors, which are often twisted together and are often surrounded by a shield.
A balanced connection, which can also be referred to as a balanced interconnection or a balanced interface, will utilize a balanced cable, and the interface circuits in the connected components will utilize the cable in a manner such that the two conductors have the same impedance between each conductor and ground.
A balanced connection will often, although not always, convey signals on the two conductors that are of essentially the same amplitude but have opposite polarities. On the other hand, if one conductor is provided with a signal and the other is provided with zero volts (i.e., ground), that still constitutes a balanced connection, as long as the two conductors are symmetrical and have equal impedances to ground.
A balanced cable terminated with XLR connectors will have a signal conductor connected between pin 2 of the two connectors, and the other signal conductor connected between pin 3 of the two connectors. The shield will be connected between pin 1 of the the two connectors, and occasionally also to the housing of the connectors.
Some manufacturers use the same wire type for their XLR and RCA cables. In those cases, if RCA connectors are used one conductor will connect the RCA center pins together, and the other conductor will connect the RCA shells/sleeves together. The shield will usually be connected to the RCA shell at just one end. That end should preferably be connected to the component which drives the cable, as Pkoegz indicated (although I think he inadvertently left out the word "not" when he said "I have found that [NOT] grounding at the receiving end and simply connecting the grounds at the sending side works best and in my view is the only real reason for directional cables").
RCA jacks are available in forms which may or may not isolate the shell from the chassis of the component they are mounted on. Well designed modern components usually utilize isolated jacks.
Components utilizing XLR connectors should ideally connect pin 1 to chassis, but in many cases connect it to circuit ground/signal ground instead, resulting in increased susceptibility to ground loop issues or other adverse consequences. See
this paper.
Regards,
-- Al