AES/EBU

A common  standard in the pro-world to connect audio devices digital.
It was developed by the Audio Engineering Society (AES) and the European Broadcasting Union (EBU) and first published in 1985

It requires a balanced and screened (shielded) cable  with nominal characteristic impedance of 110 Ω at frequencies from 0.1 to 128 times the maximum frame rate.

SPDIF is derived from this standard and intended for consumer use.

1. SPECIFICATION OF THE DIGITAL AUDIO INTERFACE (The AES/EBU interface) - European Broadcasting Union