Balanced lines are made up of and carry 3 similar elements, a positive voltage signal, a negative voltage signal, and a ground (shield). Unbalanced lines, on the other hand, are made up of only 2 elements: the audio signal and the ground. The main difference between the two is that balanced cables utilize 3 conductors to carry an analog audio signal while unbalanced cables use only 2 conductors.

In the case of a balanced line, the audio signal is doubled or duplicated and "flipped" in polarity (hence the positive and negative) to reduce noise and increase cable lengths using a phenomenon called "Common Mode Rejection". In an unbalanced scenario the signal is not duplicated and the whole signal load is carried by only one conductor.

By using 3 conductors to carry an analog audio line, a balanced cable reduces the amount of noise and electro magnetic interference that would normally be induced into the carried load when using only 2 conductors. All 3 components (positive voltage, negative voltage, and ground) that make up a balanced line use their own independent conductor. "Common Mode Rejection" is the name used to describe the phenomenon in which the design of a balanced cable, or piece of equipment, is fashioned upon that which minimizes the noise associated with unbalanced pieces of equipment.

Unbalanced cables and pieces of gear are typically less complicated and less expensive. Unbalanced isn't bad and is standard for certain kinds of equipment such as electric guitars, basses, and turntables. The main limitation regarding unbalanced lines is that cable lengths should be kept as short as possible (certainly under 25-30' maximum) in order to reduce noise and interference issues .

A shielded cable is an electrical or signal cable (audio or other) of one or more conductors (balanced and unbalanced) enclosed by a common conductive layer. The shield may be composed of braided strands of copper (or other metal), a non-braided spiral winding of copper tape, or a layer of conducting polymer. Usually, this shield is covered with a jacket. The shield acts as an enclosure to reduce electrical noise from affecting the signals, and to reduce interference with other devices.