My Onkyo amp has both Loudness and Late Night modes.
AFAIK, Loudness upps treble and bass at low volume levels. This works pretty well when listening to music at low levels (at night). This is to make the music sound better at low levels.
Late Night flattens the dynamic range so that a loud sound (say, nuclear explosion) which would be normally much louder than the background wouldn't be THAT loud - this is mostly for movies (at night).
This allows to use relatively high volume levels not being afraid that a sudden BOOM wakes up the neighbors.
It would be nice to have this feature built into MC since not everyone has it available on the hardware level.
Just MHO,
--max
I'm sure I read somewhere the feature on most Amps called "Loudness" is for this.
Raising the the bass and the high levels allows you to listen
to audio quieter while still be able hear the key parts of what's playing,
although most people just use it to get a more thumpy noise.