XLR is three pronged and eliminates some of the buzzing of RCA, that's all I know, although I'm interested in the topic.

Baluns enable impedance matching, minimize signal distortion, and suppress common-mode noise in RF and high-frequency designs ...

Just out of curiosity: what kind of impedances are required for cabling of normal audio cables and cat6 patch? I'm thinking of hacking together a quad audio cable using the four conductor pairs of a ...