why do not you break up the Poweramp equalizer for a separate Poweramp application? The Poweramp equalization options are the best and most complete, but only work on it.
with the popularization of streaming music services, Poweramp fell a bit disused (I'm not criticizing the app, it's the best offline player on Playstore!).
I have the paid version installed, but I hardly hear it, only when I need to listen to my old playlists and mostly put on a sound to give more power, because applications like Deezer and Spotify do not offer Equalizers equal to Poweramp. Especially the Spotify that has very low sound!
Think that if you can make an equalization application for any app, you're sure to make more money because the Equalizer and Poweramp will be different applications. All of the apps I tested for Playstore's qualification (without root) are fakes / placebos: none of them improves the true gain / loudness .. Creating this app I will be happy to buy it .