Walney wrote:

As someone who is not up-to-date on the newer technologies, I should
be very grateful if somebody could enlighten me as to the definition
and application of optical output.

What an optical output does is to provide a light based signal via a
high speed LED (light emitting diode) on/off (one-zero) equivalent to
what the coaxial digital RCA out connector socket does using a standard
electrical signal of similar on-offs based on voltage not light.

An optical link has the potential advantage of eliminating 'ground loop
problems' (research into these is advised if you're into hi-end systems)
since there is no so-called 'galvanic connection'.

However, if you just want to get get some kit going and you don't live
in an area where you have massive electrical disturbances, I reckon
you'd be equally happy with one or the other.

Graham