Auto Gain Control in Linux?

I found that I could bring up the alsamixer interface shown below by typing “alsamixer” into a terminal window. I was able to select the Digirig (shows up as “USB PnP Sound Device” here and in Fldigi) by clicking with the mouse, then selecting the controls with the TAB key. The left and right arrows on the keyboard move between the controls, and the up and down arrows adjust the levels.

If I understand what I should try to achieve by “tuning” is to make adjustments in the alsamixer window until I get the green level bar in the Fldigi window to get to -20db with the radio connected? I don’t think I have a mic gain control on this Baofeng 5 radio, but should I also adjust the volume knob on the radio to achieve this -20db sweet spot?