Cables are not balanced because it is low impedance, they're balanced because the audio signal and the inverted phase copy sent on the 2 live wires can be recombined in such a way to cancel out any noise that has been picked up on the cable!
-- JimHowell1970
Well, Jim, I'm trying to keep it light rather than making a 40 page treatise on balanced power. I think you have it backwards there. Low impedance cables have to be balanced. Balancing is used to mitigate the inherent short comings of low impedance signals (subjected to noise). The biggest ADVANTAGE of low impedance is minimal loss (relatively) of high frequencies that long runs of high impedance impart on the signal.
The idea is that the braided cable will be equally affected by an interference. The high and low signal are phase inverted. For example if you want to transmit a signal that at that instance is +3volts, a +3 volt signal will be sent on the positive and a -3 volt signal (inverted) will be sent on the negative. The absolute difference is 6V. Divide that by two and you get the original +3 volts.The same for the inverse -3 volts minus +3 volts equals -6 volts divided by 2 equals -3 volts.
When interference hits both the positive and negative leads it doesn't change the results. (+3volts +1 volt (noise)) - (-3volts +1 volt (noise))/2 still equals +3volts if you do the maths... no pun intended.