Also I must admit coming from speaker system and using all balanced system I do not really understand the purpose of balanced HP cable. I have to read about it.
In speaker systems it is balanced all the way up to amp but speaker cables, which one would think would be equivalent of HP cable are no longer balanced as there is no electronics on speaker side that would be required to have use for balanced signal. Does this mean that in HPs there is still some processing of signal happening at driver level?
As I said I have to read about it.
Unbalanced headphone cables share ground and only need 3 wires (if they split the ground in the headphone for the two drivers of course). It is the same with speakers, but they always use 4 wires anyway.