Xonard: a simple daemon to handle the non standard audio controls on Asus Xonar U1 devices
Copyright 2012-2015 Alessandro Pignotti

Edited 2015 Giuseppe Cuccu
Edited 2017 Nika Topolchanskaya

Asus Xonar U1 are pretty nice USB audio devices with a decent audio quality and a knob to control the volume and mute status of the device. The audio device itself is completely supported by linux using the snd-usb-audio kernel module. The control interface identifies itself as a standard HID devices, unfortunately this seems to be not actually true.

Xonard will configure the device to properly deliver interrupts when the knob is used using the hidraw kernel interface and deliver the events to the system using the uinput kernel interface. As an added bonus the blue LED blinking is set to something reasonable.

I've also reverse engineered how to configure the blinking of both the blue and red LEDs and the code should be pretty self explanatory about how to use this functionality. But this is not currently used beside setting a sane default

• Clone the repo, compile and install:
  git clone https://github.com/nan0desu/asus-xonar-u1-utils.git ~/xonar/
cd ~/xonar/
make
sudo make install
• Start the daemon:
  sudo xonard /dev/hidraw0

Compiling with make custom will make the xonar use custom keybinding, returning keystrokes not available on a standard US keyboard. Such keystrokes can be customized for advanced control.

• Follow installation instructions, substituting make custom for your make call
• Bind the keys

In Ubuntu you can add shortcuts from System Settings -> Keyboard -> Shortcuts, click on the + button on the bottom.
Here are some example bindings:

• Title: Asus U1 volume up
  Command: amixer -q -c 1 set PCM 1dB+
  Shortcut: rotate the volume knob in the desired direction
• Title: Asus U1 volume down
  Command: amixer -q -c 1 set PCM 1dB-
  Shortcut: rotate the volume knob in the desired direction
• Title: Asus U1 toggle play/pause
  Command: xdotool key XF86AudioPlay
  Shortcut: press the volume knob

Compile with make scroller. Daemon will emulate mouse scroll wheel. Scroll direction can be reversed in xonar.h (CLOCK_WISE_OFFSET and COUNTER_CLOCK_WISE_OFFSET)

• The device number can differ, check with ls /dev/hidraw*.
• The card number can differ, open alsamixer and press F6 to find out.
• Use evtest utility to monitor input events.
• To once shortcuts are set at OS level, you can switch between setups with the following:
  • make; sudo make install; sudo xonard /dev/hidraw0
  • make custom; sudo make install; sudo xonard /dev/hidraw0

When plugging the card on many Linux distros (particularly Ubuntu) and listening through analog devices (like headphones), the sound is disturbed with noises and clicks. This is due to the optical output being on by default. To fix this:

• Visually inspect the headphones plug. If you see a red light, optical output is on.
• Open alsamixer, press F6 and select the U1 card
• Navigate with the right arrow to the Digital control
• Press m to toggle it mute (will switch from 00 to MM)
• The red light should be off now. Plug in the headphones and verify if the problem is solved.

To make sure the problem does not represent itself every time you disconnect/reconnect the xonar, save the alsamixer settings with sudo alsactl store 1. If you still have problems you can check here for further assistance.

The Asus Xonar U1 is a great piece of hardware, which plays much better than you can imagine unless you have the proper setup. Try activating the optical output, getting a toslink optical cable (they're super cheap) and connect it to a good hi-fi (not so cheap) for maximum fidelity. Or just get some good headphones (cheaper than you think). Then get some high-quality music: if MP3 you'll notice the difference between a low-quality and high-quality encoding (say between 128kbps and 320kbps). Or get a CD/DVD, or flac files, and search online for the keyword audiophile. Enjoy your hardware.

Also, spend some time playing around with alsamixer. If your headphones can sustain higher volume, unmute the Loudness control: it activates the internal amplifier, use it with caution, it delivers high volume without quality loss. You can bind a shortcut (like pressing the volume knob) to this command to toggle the amplifier on and off: amixer -c 1 set Loudness toggle.

The code should be pretty safe, but consider that it does not come from official documentation, since I've found none. Don't blame me if it does harm your device or your cat: read the LICENSE before usage.