Here is a look at how unbalanced and balance audio cables work and why you would choose one over the other.
Working With Audio Cables
Digital audio recording is an interplay between physical audio recording gear and the digital software systems that you will use to mix the audio. When you are in the field you will need to use cables to connect the microphones that you are using with the appropriate recording device. These audio cables will come in a variety of formats depending on their purpose and the types of equipment that they are working with, but they are often broken down into the more basic categories of unbalanced and balanced audio cables.
Balanced Audio Cables
Balanced audio cables are, in most situations, going to be the preferred audio cables to choose. These cables hold two center conductors, not just one, for the signal that passes through it. Around those two center conductors there is often a shield that encases it, and this shield can act as a protector. One of the center conductors will be negative, the opposing one positive, and they will be wrapped together.
Balanced audio cables are by and large the standard among professional audio production and that is what you will find in most situations for prosumer to full service professional equipment. The shield itself is going to be a foundational element that ends up protecting the conductors from outside interference, such as Radio Interference. The three pin XLR cables that come standard for audio/video work and field recorders are balanced audio cables, as well as the quarter inch plugs that you find with the "tip, ring, sleeve" dynamic and are use in specifically professional situations. The quarter inch TRS cables can be found in both balanced and unbalanced forms, so it is important to investigate this further before making an assumption based on the end plug.
Unbalanced Audio Cables
In opposition to balanced audio cables are less useful unbalanced audio cables. Instead of having a positive and negative conductor wrapped together, there is only a positive conductor. This positive conductor is balanced out by the shield, which is negatively charged. Unbalanced audio cables are much more susceptible to picking up outside interference, whether radio, electromagnetic, or otherwise. This will be a problem in situations when the audio that is being recorded must be specifically clean, such as when recording field audio to go along with video or during an album recording. If you are using it just for performance, however, then unbalanced cables are not always going to be a problem. In most professional digital audio recording situations unbalanced audio cables would be unacceptable.
Though it is not universal, home stereo equipment like RCA plugs rely on the unbalanced audio cable model. Cheaper recording equipment or amplification peripherals, as well as musical plugs that will bring an instrument into an amplifier. Most of the consumer cables associated with portable media players like the iPod are also built around unbalanced audio cables.