[Audio] - "External device" is present as an "Output Device" when no monitors are connected.

[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:

On Steam Deck, regardless of a user's audio configuration, External device will always be shown as an available Output Device in Steam. If an external monitor is not actively connected, the option becomes redundant and duplicates the previously selected entry. When chosen it appears unselectable to the user as the option is automatically reverted when you navigate away from the Audio settings (see video below).

Video

https://github.com/user-attachments/assets/7d14a0c9-0779-4bdc-b642-44b06cab2596

Steps for reproducing this issue:

1. Navigate to Steam > Settings > Audio > Output Device.
2. Select External device.
3. Navigate away and back from the Audio settings.

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: "External device" is only shown as an option on Steam Deck (Gaming or Desktop in Big Picture Mode).

Actual result

• External device is visible in the Output Device list regardless of if a monitor which provides audio support is connected to the Steam Deck.

Expected result

• External device should only be visible if a valid monitor with audio capabilities is currently connected to the Steam Deck.