How to disable S/PDIF (IEC958) profiles in Gnome and PulseAudio

While I have no S/PDIF interfaces on my computer anymore these days, Gnome sound settings still shows me a list twice as long as necessary. With a few displays, DACs and Bluetooth transmitters, a list of 8 or more entries becomes a problem to select from when there a not actually that many devices present.

Can we hide or remove these?

I removed the IEC958 profiles this way on my current setup on Ubuntu 21.04:

$ pactl list cards | grep iec958 --count
29

$ sudo sed -e '/\[Mapping iec958-stereo\]/,+5 s/^/#/' \
   -i-backup \
   "/usr/share/pulseaudio/alsa-mixer/profile-sets/default.conf"

$ systemctl --user restart pulseaudio.service

$ pactl list cards | grep iec958 --count
0

I'm using sed here to match the line that contains [Mapping iec958-stereo] and the 5 lines after it to comment them out (prefix with #). I'm also creating a file named default.conf-backup because things usually get messy and we don't want to search and reinstall the corresponding package. After that I'm restarting PulseAudio for the current user. Applications should still play sound without closing and starting them again when using systemctl --user instead of pulseaudio -k. The pactl commands show that there have been 29 instances in my configuration before and 0 afterwards. When I open up Gnome sound settings I have no S/PDIF interfaces. Which is exactly what I wanted.

Some people may argue that I should have created /usr/local/share/pulseaudio/alsa-mixer/profile-sets/default.conf instead. But that did not work.