I just made the switch from Chrome to Firefox and have found this extension to be really good, although I only gave it 4/5 stars simply because it doesn't have a pre-amp slider.
I don't specifically need the slider as I have a DAC with volume control, but anyone that already has low sound could really benefit from it.

Nice, but prevents Video Speed Controller from working, even when its not on but just actively installed.

A good plugin but it does not allow the user to save and backup customized presets. There should be an import and export feature to backup all presets, so that settings can be restored (when needed) and shared between other systems/users.

It's a good extension, but there is a bug on it. when trying to rewind or go forward on YouTube the video pauses or crashes.

Very nice EQ implementation, provides smooth & clean sound quality. Would like to see some prepackaged presets for different listening venues.