20.04 – Sound output very low but jumps up when opening audio controls

Sometimes using alsamixer helps to give a more static control over the input and output volume.

First, install the alsa-tools package:

sudo apt update
sudo apt install alsa-tools

Then, run the following command:

alsamixer

You may need to press F6 to select your sound card if you have multiple audio devices.

Press F5 to show all parameters.

Use the left and right arrow keys to select a different item, up and down arrows to increase or decrease the volume. When a parameter is selected, press M to toggle mute on or off (this will be shown below the volume bar as MM when muted or 00 when mute is off).

Also, it’s usually suggested to disable or toggle the automute item OFF (I believe up or down arrow or SPACE_BAR will toggle this item).