Audio Volume of NRS games needs to be updated indeed, most of the time it becomes hard to actually hear anything at all, this is also one of the reason why people can't remember MKX soundtracks, in the end, i think it cripled most of the great themes in the game, they also need to drop the movie theme soundtracks, i really wish Dan Forden could get his shit together.
Case in reference the best soundtracks from MKX if you do some magic to turn the volume up are:
The Kove (Round 2)
Kuatan Jungle (all 3 Rounds) probably the only MKX soundtracks with MK style of composition.
Outworld Market Place (Round1 and Round 2)
The pit (Round 1 and finish him loop)
Everything else it really felt like missed the mark.