I am writing this review
1) to say "Thank you" to the one who did the "remastering" and
2) to tell those seeking a tool to amplify the sound on a given web page that my vote goes to this add-on resource.
FYI, I have found the version from a year ago was extremely helpful when listening to recordings of soft-spoken speakers. I have regarded this add-on as a treasure, lost for several months and now found again. When it was gone, I tried a similar one, but that one only worked when audio was combined with video and after a while that failed.
This one has the same great functionality as before. I have never experienced anything malicious functionally and am glad to hear this implementation is clean.

Recently I tested every audio addon, that was updated during the last 12 months. This one belongs to the „600% Sound Volume“-family, which is a solid choice since a long time. Among this family there is a lot of back and forth: The original by Aliaksandr and the first privacy orientated fork by 1fexd are gone now. The latter has two legit sucessors: The addon by Savva, wich is under rough recontruction, and this‘ conservative clone, which is not open source, but the only family member to work on Soundcloud. So, make your choice, but be aware of what‘s happening next!

it actually works on soundcloud!!!!!! and it just works all around, super good

I thought this extension was gone for ever! It's finally back?!?!?! Its so useful especially when the video's audio track is very soft and slow!!