Sound applet won't change output device

[Leon Matthews]

Using the gnome-control-centre sound applet to change the output device from the motherboard's default to an external USB device used to work well on 19.10, but does not work on 20.04 Beta.

I use a USB headphone DAC/amp on my desktop (Schiit Modi/Magni combo). Under Ubuntu 19.10 I could use the sound applet in the gnome-control-center to select either that USB device or basic audio through the HDMI cable on my monitor (it would always default to the basic audio on reboot, but that's another story) then use my headphones happily.

Using Ubuntu 20.04 Beta the sound applet shows all of the expected devices, but choosing different devices has no effect - any music then played continues to come only from the monitor. Using the 'Test' button plays sound only through the monitor also.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-control-center 1:3.36.1-1ubuntu4
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
ApportVersion: 2.20.11-0ubuntu26
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Wed Apr 15 11:44:27 2020
InstallationDate: Installed on 2020-01-11 (94 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
SourcePackage: gnome-control-center
UpgradeStatus: Upgraded to focal on 2020-04-11 (3 days ago)

In case this is useful at all, I've playing around on the command prompt::

    $ pactl list sinks short
        0 alsa_output.pci-0000_03_00.1.hdmi-stereo-extra3\
            module-alsa-card.c s16le 2ch 44100Hz SUSPENDED
        1 alsa_output.usb-Schiit_Schiit_USB_Audio_Device-00.iec958-stereo\
            module-alsa-card.c s16le 2ch 44100Hz SUSPENDED

    $ pacmd set-default-sink 1
    $ paplay Chicken\ Cluck.wav # Headphone output working!
    $ pacmd set-default-sink 0
    $ paplay Chicken\ Cluck.wav # Monitor output

Unfortunately, the command that let me listen to chickens on my headphones (pacmd set-default-sink 1) had no effect on sounds from the rest of the system (mpv and Rhythmbox tested).

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1866194, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.