Audio boost is for 5.1 audio converted to 2 channel audio. The center channel (voice dialog) will be very low when it happens so you need to give it a little boost. If the source is 5.1 audio and your player output is 5.1 audio without converting it, you won’t hear anything different. Same thing if the source is 2 channel stereo and you’re listening to 2 channel stereo.
I found the “small” setting is enough of a boost to hear voice dialog. If I use large or huge, I will sometimes get static in the audio or the audio will sound worse.
