RigPi Audio doesn't have settings of its own, but a Linux utility named Alsamixer is included with RSS for that purpose. You can also use the Audio Device Settings window opened from the Raspberry Pi Desktop applications menu found in the Preferences menu item. The driver used for RigPi Audio is snd_rpi_proto.
To start Alsamixer go to RSS Desktop and open the Terminal. Type alsamixer followed by return. The screen shot below shows the typical settings for the RigPi Audio board set up for Mic input.
•Left and right arrow keys select a setting
•M key toggles MM-OO settings
•Tab to change View (Playback, Capture, All)
•Up and Down arrow keys to change levels
RigPi Audio uses the Line or Mic Input depending on settings. The Line Input accommodates input voltages up to 2-volt peak-to-peak. The Mic input is for input levels up to .2-volt peak-to-peak. The Line input uses the left channel, it is not stereo. Input from the I/Q jack is stereo as required for Panadapters.