Found that if i change to Digital Stereo Output in the Linux sound settings area (was on Digital Stereo Output with Analog Input) it now defaults to Alsa in steam correctly and the detect button is also there in the steam Voice area.
Seems I made an incorrect assumption, I thought the big picture mode accessed via the desktop steam client (on the same system) was the same Big Picture Mode launched into on a fresh boot of the computer. On a fresh boot there is no Detect Audio option and Alsa is not selectable ;(.
Hello @Ulgrim, are you still experiencing this issue on an up to date system?
Nothing extracted yet.
Sorry if this exists already. Latest install of SteamOS Brewmaster (clean install on new drive) and booted into big picture mode. I've gone to settings and then voice and the only option is Built-in Audio (no detect devices, no other choices).
If I change back to Desktop steam I'm able to go to the voice options and select Alsa no problem. Choice doesn't appear to carry over to Big Picture.
No detect audio devices option shows (though I see that shows up on the Windows version of Big Picture). I understand that feature even in Windows Big Picture isn't implemented fully so perhaps all of this is still planned for future.