I came here because I was just playing [1] on headphones, and Firefox seemed to think that it would be a good idea to set the master volume to 100%. My ears are still ringing. At least now I know what to do.
[1]: https://en.wikipedia.org/wiki/File:AFSK_1200_baud.ogg The fix of changing "flat-volumes = yes" to "flat-volumes = no" in /etc/pulse/daemon.conf seems to be fairly easy to implement, considering the fact that this bug is blocking a great number of other bugs, and no one here apparently has to say any word against it in the comments. Is there something else blocking it? - Roland