TerraTec Aureon 7.1
The Terratec Aureon 7.1 USB is an affordable external sound card which supports optical and digital output through S/PDIF with full 5.1/7.1 surround sound. To use this card, install ALSA (which has support for this sound card). To configure the card for usage, follow these steps:
Set the card as the default device
Create the following file Template:File Rebooting or restarting the ALSA (sudo /etc/rd.d/alsa restart) may be required for the changes to take effect.
Enable volume control
This card doesn't have hardware volume control, so you need to create software Master control. Create the following file in your home folder Template:File
Again, restart alsa, then open a music player, play a file and close the player. Then check alsamixer, as you should have a Master volume control.
As you can see, alsamixer doesn't handle mute for this mixer, which is why you can use a simple mute.sh script, which stores the volume level in volume.txt. Be sure to change the file path to mute.sh accordingly. Template:File
Configure mplayer for surround sound (optional)
Add the following codec settings for mplayer Template:File
I recommend using XBMC for media playback, as most receivers do no support the AAC codec. XBMC will re-encode AAC to a common codec (AC3 probably) in realtime, so you can watch most surround sound media files. XBMC has a self-explanatory configuration system using a GUI.
To change volume using amixer and hotkeys, use the following command (for example): "amixer set 'Master' 5+"