Headphone amplifiers with coaxial input

Coaxial S/PDIF

— input for digital audio signal transmitted via a coaxial electric cable S/P-DIF. It most commonly uses an RCA type connector, but do not confuse the coaxial interface with an RCA input (see the relevant section) — they are fundamentally different standards (moreover, standard RCA cables are not very suitable for digital connections, for which a special shielded cable is desired). Other design options exist — for example, in some models, the mini-Jack socket is responsible for this input and can switch to S/P-DIF mode.

In any case, the presence of this input means that the amplifier is equipped with a built-in digital-to-analog converter and can work with a digital audio signal. The interface itself allows the transmission of two-channel and even multi-channel sound over one cable. In this regard, it is similar to an optical input (see the relevant section); in fact, "optics" is also one of the varieties of S/P-DIF. The main differences are that an electric cable (even shielded) is more prone to interference, but does not require as delicate handling as fiber optics.