Is it possible to do something like https://www.reddit.com/r/lifehacks/comments/3hub4x/movie_music_too_loud_but_dialogue_too_quiet/ for the Raspberry Pi? Action scenes are super loud in comparison to the dialogue.
There is a boost centre channel option
Extreme volume differences between action scenes and dialog is usually an indication of a bad rip, although it is quite common.
To compensate for this try increasing Volume Amplification to about 9dB in the audio onscreen controls, and in Settings increase center channel boost to about 3dB.