So first of all, you have to download this application on your Windows computer. It also allows you to increase your computer volume at maximum level. With the Equalizer, APO is the best Windows based application that you can install on your computer to manage your all audio features. Here we are talking about the “Equalizer APO,” the windows OS based software that allows you to manage your computers audio sound. Here are a few steps to increase the headphone volume at maximum level on your Windows based computer or laptop. Sometimes you find that the headphone sound volume already set at the maximum level, But the headphone does not offer sufficient the sound that you expect from it. If you use a headphone while watching movies, videos, or playing high-end games on your computer.