Change the audio output device in Firefox

Solution 1:

One thing you can do since I had the same issue is set your OS to use a virtual cable as the default device.

Adobe Flash uses windows defaut and in doing this you will have set firefox to use the VAC for flash based objects (I have verified that flash is sending the audio not firefox for flash based objects or movies)

Then simply use a repeater to send that VAC to your original sound device (soundcard) so you will hear everything like normal but have a VAC tied in the middle that you can work with to do other things.

Ultimately, what worked best for me was to just use a secondary device and send it to my computer with a line-in (use my hp touchpad) this let me drop the huge net of VAC and Repeaters that was causing a delay in my recordings and also let me control that external audio source while in game easily since its on a separate device.

Solution 2:

Software solution for this: https://github.com/audiorouterdev/audio-router

You can choose output for each app.