This is feature that I should request long time ago. I tried normalize audio volume using Sliders Controls for each game but some games have so many channels that I've give up. Second problem was lost sound after boosting volume above 1 or cracklings. Normalize volume through master slider is faster but this option is not saved unlike Speakers options and it cannot be raised above 0 db.
I know that saving might be a problem but probably at least making audio boost above 0 db should be possible.