Audio line out not working

I have a custom built desktop PC. When I plug my speakers into the rear audio port on the motherboard, I don’t get any audio output. In pavucontrol it says the “Line out” output device is “plugged in”, and it shows the levels in the UI as I play audio, but I hear nothing. If I switch to my front panel audio port and switch my output in pavucontrol to “Headphones (plugged in)”, it works fine and I can hear audio. My immediate thought was that it was a hardware issue, but I dual-boot Windows 11 on the same machine, and both ports work fine in Windows.

Here’s I think the only relevant bit from my NixOS configuration:

      services.pipewire = {
        enable = true;
        alsa.enable = true;
        alsa.support32Bit = true;
        pulse.enable = true;

      security.rtkit.enable = true;

      environment.systemPackages = with pkgs; [

Any tips on how to debug this or what might be going wrong?

Solved with some help from a friend. I had to use alsamixer to turn off “Auto-Mute” on the output, not sure how that got enabled.