O.K., your audio signal is nothing but a wave (Dude!) with a positive cycle and a negative cycle... with me so far? Anyway, imajine spliting off the positive part and sending it to amplifier "A" and likewise sending the negative part to amp "B" (there are actually two amps for each channel which is why Balanced costs more). Onward... Now that you have the two halves isolated, you compare them to each other (the ground-wire value is used somehow as a reference. ever notice balanced interconects have 3 wires?) with the understanding that they should be complete opposites. If anything is found in common, it is assumed to be hum or noise of some kind and stopped dead in its tracks (does not get out of the amp). The result is a very quiet background for your music (Shazam)!
