Let me check the WirePlumber settings documentation and look for the exact mechanism.

The blue Yeti Nano issue is well-documented. Let me check how to present the fix steps properly.

What's actually happening

The Blue Yeti Nano is a duplex USB device: besides the microphone it registers a playback card (its headphone/monitor jack), so Linux sees it as both a mic and a sound output (Ask Ubuntu). On Debian 13 (GNOME), audio is managed by PipeWire + WirePlumber, which stores and restores profiles, routes and their volumes per device whenever the device graph changes (WirePlumber docs). When the Yeti Nano appears, WirePlumber churns profiles/routes around its output, and that's what gets your laptop speakers' route volume re-applied at 0 — even though the default output device itself correctly stays on the speakers. This is a well-known Yeti trait: multiple users report other outputs stopping or dropping to zero whenever the mic is plugged in, and the fix that worked was configuring the Yeti as mic-only instead of duplex (r/linuxaudio, r/linuxmint). The Nano in particular has a reputation for being flaky with PipeWire (r/archlinux).

Why this works

• Setting the profile to input-only makes WirePlumber's device.restore-profile remember your choice and re-apply it on every replug/reboot, so the Yeti never creates an output sink again — no output churn, so the speakers' volume is never touched (WirePlumber docs).
• Wiping ~/.local/state/wireplumber removes the stale saved route record that may already contain volume 0 for the speakers (this state file is exactly where WirePlumber persists per-route volumes). You lose saved per-device volumes and default-device memory once, then they re-save normally (Unix.SE).

You can confirm the diagnosis before/after: wpctl get-volume @DEFAULT_AUDIO_SINK@ while plugging the Yeti in, and grep -i -A4 speaker ~/.local/state/wireplumber/default-routes to see if a 0-volume entry is stored.

Extra hardening (optional)

If you want the Yeti's output blocked even if state gets wiped again, create ~/.config/wireplumber/wireplumber.conf.d/51-yeti-input-only.conf:

monitor.alsa.rules = [
  {
    matches = [ { node.name = "~alsa_output.usb-Blue_Microphones.*" } ]
    actions = { update-props = { node.disabled = true } }
  }
]

Then systemctl --user restart wireplumber.

One more note: GNOME's login screen runs its own PipeWire/WirePlumber instance, and a greeter's WirePlumber can reset stored volumes which then gets picked up by your session. If you notice volume resets around the login/lock screen too (with the Yeti still plugged), mask those units for the greeter user: sudo systemctl --user --machine Debian-gdm@ mask pipewire.service pipewire.socket wireplumber.service (Unix.SE).