If booted with headphones in, sound comes from them and speakers

[user18130814200115]

+1

I can resolve it by re-plugging the headphones into the 3.5mm jack, at which point sound only outputs through the headphones.

By default, I think manjaro adds a systemd service that switches the output between analog-output-speaker and analog-output-headphones.
If the output is set to analog-output-speaker and anything is plugged into the 3.5 mm jack, then the sound will come from both.

You can switch the output manually with:

Code:

pactl set-sink-port alsa_output.platform-es8316-sound.stereo-fallback analog-output-headphones

I personally have a script to toggle between the two outputs bound to a hotkey.