This add-ons is pretty handy if you want more audio even if you are currently using low system-wide audio settings on your desktop.

Works perfectly on all site, however if possible a dark theme toggle for the extension window would be nice to have.

Toggle for some sound mode types would also be nice like Sound Boost or Vocal Boost in Extension Window along-with some higher percentage sound levels like 200% or 300% etc.

Overall, it's a great add-on for Firefox and highly recommended to anyone looking for a good volume control on web browser.