Music Booster - Volume booster

Use Music Booster - Volume booster pro at your own risk. Playing audio at high volumes, especially for a prolonged amount of time, can destroy speakers and/or damage hearing. Some users HAVE reported destroyed speakers and earphones. If you hear distorted audio, lower the volume (but it may be too late). By installing this application you agree that you will not hold its developer responsible for any damage to hardware or hearing, and

This is not for adjusting the speakerphone volume in phone calls (that has its own boost, I think), but for adjusting the volume of music, movies and apps.

When you set the boost to zero will be off. The notification icon is just for ease of launching. If you don't like seeing the notification icon when It is off, just go to Music Booster - Volume booster pro's Settings and set it to appear only when Music Booster - Volume booster pro is running.