You also have the built in EQ settings in Media Audio Effects. I just finally plugged up in my car and wow sounds so good. These settings are system wide so not confined to a particular audio app. My Pandora never sounded so good. Same car, same cable, new sound.
I said system wide. Pandora is not a stock app. Neither is Spotify, TuneIn etc.That's only if you use the stock app. I use playerpro and it has the equlaizer too which make it sounds really nice as well