On a beige G3 with OS 9.1 - Running sound to my home stereo with the RCA cables from the RCA output jacks on my machine, but the built-in speaker plays also! (unlike plugging into the headphone jack, which turns it off)
In my Sound control panel, I ONLY see "built-in" as an input option, no "external", so "built in" stays selected as a default, (which I assume is why it still plays).
How come there is no external choice? Do I need to re-install the control panel or some other thing to add this choice? Or is it something the system senses somehow? any help appreciated!