nope your not missing anything.

Machines like the Quadra 610 had Audio pass-through, from the internal cd drive.

( To get cd audio patched into the main sound system )

but externally you have the head phone jack or on the back some ROM's had L and R RCA out jacks.

now if you wanted to make a RIG you could get a RCA to 3.5mm female audio jack then get a 3.5mm male to male audio cable and connect it into the mic port.

get the cd audio on the internal speaker of your " Enhanced Audio" Classic II