Excellent, wow! I hesitated to try this because there are few users/reviews, but it is perfect.

Advice:
1. I love that you've made the "<3 Support" button optional, and I want to leave it enabled because I like the heart symbol. But leaving it enabled takes up a notable block of screen real-estate. Maybe you can put it somewhere else?
2. The Voice/Bass boost features work very well, they are clearly noticeable and I will continue using them. But I'd like that whole row to be optional.

by far the best firefox volume booster👍cheers mate