YouTube Audio Equalizer and Amplifier is a Firefox extension designed to provide users with advanced audio control for YouTube and YouTube Music. This subscription-based tool allows users to boost or reduce specific frequency levels, offering a granular approach to audio equalization. With controls for a wide range of frequencies, including bass and treble adjustments similar to traditional audio equipment, it caters to diverse listening preferences.

The extension features a user-friendly toolbar button that opens a popup for easy audio adjustments. Users can choose from approximately 12 presets or customize their own levels, and it supports profiling for saving different audio settings. Additionally, the extension includes a global volume control to manage profile levels effectively. Note that it only functions on YouTube pages and must be enabled from the popup window.