Recently I tested all audio addons, which were updated during the last 12 months. 1000% Sound Booster by username32480 is a simple, modern alternative to the „600% Sound Volume“-family of forks (e.g. lefriend, savva, 1fexd). In general it does the same, while the code is much slimer: 33kb vs 84-115kb. An unusual permission for webNavigation is required, which may help on sites with multiple media frames. The max boost is impressive, but hard to enjoy, as the clipping grows exceptionally high as well.