Alternative Sound Processor/Equalizer for Galaxy S6

Recently acquired a Sprint Galaxy S6 (Android 5.1.1). Not too happy with the sound quality I'm getting through headphones using the built in equalizer and Sound Alive. Tried installing a couple of sound apps called Noozxoide and Audio FX Widget. Neither of them will work though with Spotify or music player apps (e.g. Poweramp). I even tried disabling Sound Alive and they still wouldn't work (they will activate, but will not affect sound). Is there any way to get equalizer apps to work on the S6 or am I stuck with Sound Alive?

Thanks.