Linux Mint, just updated to FF 57.0.3 from 55.something hoping to fix the sound issues. It didn't. The videos play, but no sound comes out of my Logitec USB headphones. PulseAudio is installed Music plays off the hard drive via several players The headphones show up in the volume control settings boxes. https://www.youtube.com/html5 shows that my browser if working perfectly (all checkboxes are checked).