I just purchased an LG Leon phone and was surprised to find out that LG phones don't have any EQ implementation. I installed Equalizer FX as recommended here, and am now much happier. Before, when I connected to my car stereo, the treble was so screechy any increase in volume became quickly intolerable. But EQ FX has successfully fixed the problem! However, I did have a minor issue with EQ FX initially not affecting the sound output, despite any changes to the frequency sliders. It wasn't until I toggled the Loudness effect on an off that my phone "woke up" to the fact that EQ FX was installed and running. Then, I could change the EQ. So much better now. Thank you for the lead to this app!
Oh, and as others have mentioned, I also noticed the EQ FX icon in the notifications tray constantly. I believe this to be a "necessary evil" so that the application remains running and effective to my music applications. I'll deal with it.