There is no fundamental difference in sound quality between "balanced" and "single-ended" circuits. The major upside to balanced circuits is that they are less susceptible to correlated noise picked up by interconnects, ground loops and power supplies since the balanced circuit floats inside its own insulated world.
Agreed.
I would add that balanced usually has a higher signal level (pro audio).
I would add that ground loops are quite often a problem if you talk about audiophile quality with recordings that have tremendous dynamic range. However for your average Green Day of Red Hot Chilli Peppers hyper-compressed releases there is unlikely to be any audible difference between RCA and balanced.