Hi Tom,

You can scale the audio level up using pactl, first you'll need to work out the sink (audio destination) name for your bluetooth device. You can do this by running:

This should help find something of the form "bluez_sink.00_00_00_00_00_00" (where 00_00_00_00_00_00 is your bluetooth address).

Once you know what this is you can scale the volume by running:

Where 2.0 is the increased volume level.

This can also be carried out with the main audio sink (sink.primary) to increase the volume from the phone speaker, I'm not sure I'd recommend it though for fear of doing some damage.

I'm not certain how long the change will last (I've only tested it quickly as an experiment), I expect it'll at least get reset when restarting the phone, so you might want to set up a little script to do this and then create a .desktop file in /usr/share/applications to run that script (see the existing .desktop files for an example of how these work). That way you can have a little launcher icon trigger it for you.

Also, you probably want to test values with the headphones away from your ears so you can get a feel for the scale without accidentally deafening yourself .

Hope that helps .