Its very nice

It does really boost the up the volume just by sliding the volume bar in the 100% tab.

I don't know why, but it doesn't stay muted when I set to 0%. On twitter, for example, when I open a video and set to 0% it works, but then I open another video and it's not working anymore.

so good , literally increases volume loads.

genial !

My laptop audio was bad tell i got this extension.

Edit:
WARNING: DO NOT USE.
I downloaded the xpi (add-on file) and was looking in the source code, its definitely doing something dodgy. It's downloading a file from the devs homepage called https://ad.resourcefulman.net/banner/ad-locations.txt and seems to be injecting adverts etc into the web pages, and redirecting other pages. I am reporting this add-on.

Original post:
I am pretty sure this addon is malicious.
When visiting AliExpress, I get getting redirected to weird versions of the site. After some investigation I found reddit post stating "Best.aliexpress is known to be a redirection/affiliate link. Clean all cookies of your browser. then revisit aliexpress." After I used "forget site", it started happening almost immediately again. I disabled all my add-ons and re-enabled them one at a time, I found that after re-enabling "600% Sound Volume", the redirects would consistently happen. If I forgot site, and had 600% addon disabled, I could browse Ali indefinitely, however as soon as I re-enabled 600%, all subsequent Ali browsing would be getting redirect to the affiliate link.

it bug the videos and make problem of mime type not found in site videos Mozilla firfox and the sound restart automatically and you have to adjust it again and again

Make too quiet movies enjoyable.

Works perfectly for Youtube and Facebook videos. Just shy of five stars because this app's "homepage" redirects to a regular spam-riddled blog, making the app kinda untrustworthy.

Great extension, helps me a lot , i dont need to buy other speakers