A free app for Android, by FeniKsenia.

Loud Volume Booster for Headphones with Equalizer is an app for Android. It is a tool for people with hearing loss and those who want to listen to their favorite music at maximum volume. It will also help you to improve the sound quality of your devices. 

This tool has a built-in equalizer, which will help you to adjust the sound to your preferences. You can use the app as a booster for your music players and video players. It can also be used as a booster for social media and internet browsers. It can also be used for gaming.

This app can be downloaded on Google Play Store for free.