Firefox Developers Edition only uses the internal soundcard

I’m using the Developers edition on windows 10. I can’t change the sound card the browser use. Only works with the internal (default) card, even when I select any other sound card on windows. Chrome, Edge and “normal” Firefox works as expected, but that’s not the case with Developers Edition.
Any ideas?
It’s working this way at least for the last 10 or 12 updates. Now I have the 109.0b2 (64-bit) version.
Thanks in advance!