Speaker idea

[slyecho]

Alsamixer is the way to go to get all the settings for volume. Press F6 to select the rockchip sound card, then in Manjaro I can see that there is Headphone and Headphone Mixer that mainly control the max volume level..

Also check Playback Polarity, change that to R Invert or L Invert, on Manjaro that is already default, but check with a speaker polarity test sound clip.