Is it a software or hardware?
Software. I believe the stock one is MusicFX, and most serious music players have their own. Personally I use N7player.
The thing I hate about most equalizers on Android is that once enabled maximum volume is decreased although the shape of the sound does change. Sometimes I just want more volume. .. for that a custom kernel and dsp manager are needed.
Sent from my SM-P900 using Tapatalk
Firstly, disable Adapt Sound in the application manager. It evens out the volume of all audio.
I've also disabled musicFX.
Some music app equalizers have a pre Amp increaser which boosts or decreases the volume to a level of your choice. Screenshot included.
That's N7 player, by the way. It has one of the more extensive equalisers I've come across. (those are the settings on my Note 3 but that's beside the point).
Sent from my SM-N9005 using Tapatalk 2