this limits ONLY when the sound gets too loud, it will not affect audio below the set limit, for example if people are talking in a movie and the limit is above that, you won't hear any difference, but if the movie starts playing really loud music, you'll hear a bit of crackling but the music will be at the volume of the limit you set and you'll still be able to hear and make out words fine if something is not dramatically over the limit
pre gain: effectively a volume booster prior to any limiting of audio
hard upper limit: the limit of volume the audio can reach before limiting takes effect, set to max for no limiting at all
