Do you have more details on the Firefox problem?
I have a WebRTC project that is currently in standby (priorities changed) and one issue that I have not been able to troubleshoot was an inability to send audio from Firefox while it somehow worked on Chrome.
It works fine in Firefox (send and receive) as long as you don't need to play on multiple output devices. Currently you can enable a feature flag, use enumerateDevices() and play audio files on specific devices, but you can't hook up WebRTC streams to the devices.
Alex Chronopoulos: "We keep it off because it does not work for everything. It works when we playback a file but not for webaudio or WebRTC. We want to add those too and we keep it off till then."