Sounds like it's doubling the audio.

Holy Shiznozzles! This works in realtime, and like instantaneous response on modification of values. I hope this gets option to maintain custom saves based on websites like Audio Compressor by vatara, but overall the finesse and visual feedback of this overtakes the cake from vatara's extension. Finally a good F***ing range compressor extension that actually does what it says!

Seems to work fine with Netflix and Plex.
As of writing;-
Sometimes the VU meter doesn't show and you need to disable and re-enable the extension when it stop working (when you switch tabs and play different content), but otherwise it's a really solid start!