How to change volume curve mode natural/linear/logarithmic

Using volumio on RPi3. How can I change the volume curve? Right now volume is very low under 60, only gets loud last few steps under 100. From what I read in other posts there should be a curve choice in playback options menu, however I can’t find it in any of the menu’s?

The setting you are looking for is in playback options. If you don’t see it, you must enable “Full configuration” from system settings.

Like so (see screenshot)? It’s not there - or is it in a different part?

I think I’m aware of where it should be. It just isn’t there. This is not a known issue (with a known fix or work-around)?

Anybody? Bug or am I missing something?

I have a Pine64 board that I am using now. Try to change Mixer Type from Software to Hardware and then click Save. After the system shows an update, Volume Curve Mode will appear with a selection of Natural or Linear. After you have selected one, click Save again and play a tract.

I was not aware hardware volume control was required for the curve control option to be available. Thank you!