How to choose audio device for Firefox?

I have multiple audio devices and would like to switch between them on occassion. I can't however find any option to change the device in Firefox.

I've tried pavucontrol, even restarted Firefox, but the fallback device is no chosen for audio. I'd tried the Phonon settings and placed my desired device at the top of the list for Audio Playback but Firefox still isn't using it.

Ideally I'd like to switch while running Firefox but I could live with needing a restart, or using a separate profile.

NOTE: The same problem exists for recording, but at least on pages needing the mike it asks which device to use. There still doesn't appear any way to change this afterwards however.