Coaxial and optical cables are used to make audio connections between a source such as a DVR, Blu-ray Disc player, game console, and other components such as an amplifier, receiver, or speaker in home entertainment setups. Both cable types transfer a digital signal from one component to the other.
Not all audio equipment supports both options, so you may not have a choice, but if you do, you want to make an informed choice about which cable will perform best in your home. The answer varies depending on the source you ask, and many professionals agree that the difference in performance is usually negligible. To make the most informed decisions, some basics about coaxial and optical digital cable connections are useful to know up front.
Coaxial Digital Audio Cables
A coaxial (coax) cable is a shielded copper wire that is manufactured to be rugged. It is a single wire that can transfer a signal, unlike other wired components such as speakers. Coaxial cables do not require being connected to a specific orientation. Each end of a coaxial cable uses familiar RCA jacks, which are reliable and stay firmly connected.
Coaxial cables may be susceptible to radio frequency interference (RFI) or electromagnetic interference (EMI). If any existing hum or buzz sound problem is present within a system, such as a ground loop, a coaxial cable may transfer that noise between components. Coaxial cables are known to lose signal strength over long distances, which is usually not a concern for the average home user. However, if the distance is an issue, then optical cables are the better choice.
Optical Digital Audio Cables
An optical cable (also known as Toslink) transfers audio signals via light that is beamed through a glass or plastic fiber optic medium. The signal that travels through the cable from the source must first be converted from an electrical signal to an optical one. When the signal reaches the receiver, it undergoes conversion to an electrical signal again.
The decision about which cable to purchase is most likely based on the type of connections available on the electronics in question. Not all audio components can use both optical and coaxial cables.
Some users argue a preference of coaxial over optical, due to a presumed improvement of overall sound quality. While such subjective differences may exist, the effect is likely subtle, notable only with high-end systems, if that. As long as the cables themselves are well made, you should find little performance difference between the two types, especially over short connection distances.