I'd forgotten about those little cables. If I recall correctly, they were small round cables, with maybe four conductors and a little flat connector with a clip?

4-conductor audio, generally.

Later on there was a generation of two-conductor cables that used SPDIF/PCM Audio instead of analog audio for better fidelity.

I vaguely remember CD drives with a headphone jack output!

(E.g. this one: https://pavel.network/using-cd-drive-as-poor-man-audio-playe...)