Can anyone direct me to a guide for correct Belight settings to convert ac3<>wave without changing the volume?

My main goals are: converting 5.1 audio to individual wave files (for music CD purposes); and fixing problems with ac3 (cleaning up, making mono into stereo, or adding an extra audio track) then remuxing.
I've been using Belight 22beta9. If no settings are clicked, results are very low audio.
For the 5.1 music projects, I usually tick the "Post Gain" (though all 3 gain settings seem to produce the same, very loud wave) and edit the waves with wave editor. Should I be using a different setting, such as one of the boost options to bring out the sound better?

For the ac3 projects (where I'll be remuxing the audio back to the dvd), sometimes the "Gain" settings seem too high, so I leave it unchecked (getting very low wave audio) and then boost it in a wave editor. Instead of doing that, is there a setting in Belight that would produce an equivalent volume level?

Would the slightly newer 22RC1 version do any better?
Thanks for any enlightened help.