Fantastic!
I downloaded this app because I got a new Bose Soundlink Mini II Bluetooth speaker and I needed to dial back the bass a bit on some songs to control distortion (It wasnt cheap so I dont want to blow it!). The app did great for that, but whats even more, I discovered it was also capable of making my trucks factory audio system really sparkle as well. It really crisped up the highs and added rich details that I wasnt hearing when just using the standard Apple Music app. Its absolutely amazing for free, and I am going to upgrade to premium with my next iTunes card. I imported all my songs to Equalizer+ and now its all I use!
Redneckbassin about Equalizer+ HD music player, v2.4.1