Trying to fix front i/o headphone out overriding audio line out

I just started running Ubuntu 20.04, MATE 1.24.0 on my desktop. my case has a front i/o with audio out and microphone in, and I typically use these for my razer headset with a headset/microphone splitter.

On the rear i/o panel audio out I have a set of (stereo) speakers plugged in. Now, on Windows I haven't had any issues switching these outputs, but in Ubuntu it seems like the headphone out is taking over any time it's plugged in, regardless of what output I have selected from the drop down in sound settings.

Now I don't really mind unplugging the headphones to get the speakers to work, but it would be nice if there were a solution that could resolve the issue.

So to clarify and simplify: speakers in the rear i/o work fine when the headphones in the front panel i/o are unplugged, but the output defaults to headphones when they're plugged in, regardless of settings.

Anybody out there know where I'm going wrong here? Thanks in advance!

• motherboard chipset: Intel® Z490
• motherboard audio: Realtek® ALC887 8-Channel High Definition Audio CODEC

Solution 1:

SOLVED (mostly)

Turning off automute in alsamixer sends the audio signal to both ports simultaneously and you can then use the mixer to mute one or the other.