A balanced interface, whether low-level (interconnect) or high-level (amp output) means that there is no signal-ground reference. When a differential signal swings positive on one leg it is simultaneously swinging negative on the other leg. Ground is used only for shielding & does not carry either leg of the signal. Advantages are noise-immunity esp. with longer interconnects, and 6dB greater signal level than unbalanced. My full-balanced power amp. is dead quiet, compared to the very low-level noise of another amp which is unbalanced. Cost is a factor in balanced designs because there are more electronics involved. No need for any 'special' sources. Digital outputs (from a CD player) may be either unbal. or bal. just as analog connections can be done either way. An industry standard impedance for bal. is 600 ohm, vs. unbal. interfaces which vary.
Balance ??
I want to understand (in layman's terms) what the term "balanced" means. I see amplifiers with balanced outputs and balanced interconnects. Do all amplifiers have balanced imputs ?? Do you need special digital source equipment with balanced outputs ?? Is this different from a "digital" connection ?? Help !! and Thanks