[Audio] - Output volume sliders do not visually update when plugging or disconnecting a 3.5mm audio device.

[ZereoX]

Your system information

• Steam client version (build number or date): 1731433018 (Stable / Beta)
• Distribution (e.g. Ubuntu): SteamOS 3.6.20 / 3.7.0 (Deck) and Manjaro w/ Gnome 46 (Desktop)
• Opted into Steam client beta?: Yes. Stable and Beta are currently on the same release.
• Have you checked for system updates?: Yes
• Steam Logs: steam-logs.tar.gz
• GPU: AMD Van Gogh RDNA 2.0 (Steam Deck) and RX 7800XT (Desktop)

Please describe your issue in as much detail as possible:

When a 3.5mm audio device is connected or disconnected, Steam does not visually update the various volume sliders (Audio Settings, Quick-Access Menu, Volume OSD). The volume sliders will visually remain at the level they were previously set until the user manually adjust the volume (the sink volume actually needs to change for it to be visually reflected). This issue is not present when connecting an external audio device such as Bluetooth headphones (see video below).

Video

3.5mm :x:

https://github.com/user-attachments/assets/895307de-c91c-4248-9b22-af8b828ceb9c

Note: At the 12 second mark, I press volume Up ("+"), but because the audio level is already maxed out it did not visually update until I first lowered it.

Bluetooth :white_check_mark:

https://github.com/user-attachments/assets/e0292a7f-fa0b-45b0-8a55-6221bc28eef9

Steps for reproducing this issue:

1. Turn the Steam Deck Speaker volume all the way up.
2. Plug in a 3.5mm audio device.
3. Turn the volume all the way down.
4. Unplug the 3.5mm audio device.

Reproduction Rate: 5/5

Affected Platforms

• LCD / Jupiter: Yes
• OLED / Galileo: Yes
• Desktop Deck-like session (gamescope -e -- steam -gamepadui -steamdeck): N/A
• Desktop: N/A

Note: The issue is specific to Steam Deck as on Desktop the built-in audio doesn't override the default device when connected.

Actual result

• Volume sliders may incorrectly reflect the on-board speaker volume when a 3.5mm audio device is disconnected and inversely the 3.5mm when it's plugged in.

Expected result

• Volume sliders are automatically updated to reflect the volume of the active sink when switching between the on-board speakers and a 3.5mm audio device.