pulseaudio – Headphone Sound Output Gets Mixed with the Line-Out Output (ALSA driver issue?)

I am having the EXACT same problem as is described in this question: Headphone Sound Output Gets Mixed with the Line-Out Output.
Unfortunately, that question does not have a posted answer. I am not sure that posting a question in this way is appropriate (I’m new to these forums) but I’ve been trying to figure this out for a couple weeks with no luck. Any suggestions on solutions or more proper methods to follow up on another question that’s been posted would be greatly appreciated!