I’ll take a stab at this. My guess is that for all files the player will try to keep volume spikes at a minimum reguardless of what audio codec was used in ur video file, wether it be DTS and so on. Now my belief would be that since this is a Dolby tech being used your results would be mixed with DTS or MP3 stereo an so on. The option would try to compensate reguardless of how well it can actually do it. Only compatible files would then be anything or possibly just some depending on the requirements in the form of Dolby Digital. Another guess is it’s mainly for 5.1 and above bc if u don’t have a full surround setup it could get quite annoying when u can’t hear dialect and you turn it up then a gun fight follows making u go deaf and scaring the **bleep** out of you.
I would also assume that Dolby has a way of knowing from the get go ur audio source and created some super algorithm for their codec specifically so that this works effectively for their own. Then all other audio codec it’s less effective and could definitely take away from your movie experience. Now to the maximum option this would obviously be for all files as maximum is going to try to normalize all audio as much as possible and make things a lot more consistent as for volume of the movie, why on earth anyone would want that is beyond me.
My opinion if u do have surround set up don’t even bother just leave this off. If you don’t then consider playing around with the option for compatible files only first and run that with some DD audio and see how u like it then u can try the one for all and see the effectiveness of this feature up against some DTS audio. And as personal opinion goes stay the **bleep** away from maximum, it would be totally deservicing the sound effect producers and the effect of music and everything audio adds to a movie.