The only problem is this extension "forgets" the sound setting. when you open a youtube video in a new tab, the settings are gone. you have to stop the video, click on the icon, then max the sound setting again. Great extension, annoying problem.
Awesome extension that fixes the poor sound volume of my 2011 MacBook Pro. I would give it 5 stars, if it were to permit speed controls. Currently, it always resorts back to 1x speed for videos when changing the gain.