Fix for FiiO K3 auto power-off on Arch Linux

The FiiO K3 has an auto power-off "feature" or low power mode which disables it when there is no audio signal keeping it alive. It will make an audible click every time a new sound is played, like a notification. The sound gets cut off because of the startup delay which can be annoying.

This workaround fixes the auto power off "feature" by constantly playing null audio via ffplay.

How it works

1. The udev rule triggers if the FiiO K3 is added/removed from the system and executes the script fiio-k3-fix.
2. The script will try to get the current user running pulseaudio and start or stop the service accordingly.
3. The service runs ffplay to constantly play null audio which keeps the FiiO K3 alive.

Install

Disconnect the FiiO K3 and run the following commands to install the fix.

# add service
cp fiio-k3-fix.service ~/.config/systemd/user

# enable service
systemctl --user enable fiio-k3-fix.service

# udev script
sudo cp fiio-k3-fix /usr/local/bin
sudo chmod +x /usr/local/bin/fiio-k3-fix

# add udev rule
sudo cp 91-fiio-k3-added.rules /etc/udev/rules.d

# reload rules
sudo udevadm control --reload

Testing

Connect the FiiO K3 again and turn it on. The service status should now show ffplay running.

systemctl --user status fiio-k3-fix.service

$ systemctl --user status fiio-k3-fix.service
● fiio-k3-fix.service - Fiio K3 Fix
     Loaded: loaded (/home/r15ch13/.config/systemd/user/fiio-k3-fix.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2021-07-17 22:50:16 CEST; 3min 30s ago
   Main PID: 84870 (ffplay)
      Tasks: 38 (limit: 38451)
     Memory: 8.7M
        CPU: 1.379s
     CGroup: /user.slice/user-1000.slice/user@1000.service/app.slice/fiio-k3-fix.service
             └─84870 /usr/bin/ffplay -f lavfi -i anullsrc -nodisp

Jul 17 22:50:17 Bluescreen ffplay[84870]:   Stream #0:0: Audio: pcm_u8, 44100 Hz, stereo, u8, 705 kb/s
Jul 17 22:50:38 Bluescreen ffplay[84870]: [47.9K blob data]