As an Ubuntu Linux user (10.04.2 LTS), I, too, couldn't get bit perfect audio out of my Asus Xonar STX card to my new W4S DAC-2. Everything I played (16/44. 24/96, 24/192) went out as straight 16/44 digital audio. It seems that many Linux users (including myself) don't realize that most modern Linux distros use PulseAudio and PulseAudio, by default, is set to down mix all digital audio to 16/44. So no matter what your sound card is capable of, it will down mix all of your digital output to 16/44 unless you make it do otherwise.
I'm not sure what's going on with the forum tonight, but I am only being allowed to log in to the Basic editor so I can't post a "Howto" I wrote which might help you. So, I will try to outline a few ways to get bit perfect audio out of your computer. (The first 3 worked for me) You didn't mention what flavor of Linux you are using, so I can't say what works for me will work for you. So here goes:
In all cases make sure that in Linux: you set your hardware for digital output, your volume control is set to 100%, and that any other sound features such as “replay gain”, mixers, system sounds, equalizers, are all disabled. You do not want any manipulation of the digital audio stream inside the computer.
OPTION 1:
Step 1: Obtain a copy of "gmusicbrowser" ver 1.1.6, music player. For Debian based distros, it can be downloaded from: https://launchpad.net/ubuntu/+source/gmusicbrowser or http://shimmerproject.org/projects/gmusicbrowser/ or http://gmusicbrowser.org/download.html
In Ubuntu it can also be installed as a PPA (personal package archive) by opening Administration > Software Sources and adding "ppa:shimmerproject/ppa" (omit quotation marks). https://launchpad.net/~shimmerproject/+archive/ppa
Then open Synpatic Package Manager and search for "gmusicbrowser", select it, and click apply to download and install it.
Step 2: After installing gmusicbrowser, start the program and enter "Settings" menu. Go to the "Audio" tab and for output device select "ALSA". On the same "Audio" page, select "advanced options" and for "alsa device" enter "hw:0,1" (omit quotes).
IMPORTANT NOTE: you need to determine what your Linux OS considers the digital output for your sound card. It may not be "hw:0,1" in your case. To do this, open a terminal window and enter the command: "aplay -l" (no quotes). You will get a list, look for the digital output for your sound card. For the Xonar STX the output reads:
card:0 STX (Xonar STX), device 1: Digital (Digital)
subdivces: 0/1
Step 3: adjust all other settings in gmusicbrowser and play a 24/96 track. You should be getting true bit perfect output. In my case, the W4S DAC-2 has a display to confirm this fact.
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OPTION 2:
You can try the same thing with "Quodlibet" another very good Linux music player.
QUODLIBET music player – digital output via Asus Xonar STX card:
Open Quodlibet and click on: MUSIC menu > Preferences > Player
In the Player tab's “Output pipeline” box enter: alsasink device=hw:0,1
Click the “Apply” button and you're done
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OPTION 3:
Additionally, you can try MPD:
MPD (music player daemon):
MPD is a very popular music player daemon for Linux. One installed, you can use a number of different client gui's to control playing your music (i.e. GMPC and ARIO are 2 popular clients). All the software can be found in the Ubuntu Repositories. Install MPD + the MPD extra plugin and at least one client (GMPC).
To get MPD to send bit perfect audio to an external DAC, you need to make a few modifications to the default “mpd.conf” file located in the /etc directory.
Open a terminal and enter: gksu gedit /etc/mpd.conf
This will open the mpd.conf file for editiing.
1. At the beginning of the mpd.conf file, for the “music_directory” path enter the path to your music files. For most users this will be /home/your_user_name/music. NOTE: mpd seems to prefer that you keep you music files in top level folders, so if you make a lot of subfolders, mpd will have a tough time trying to index your music. In other words, it's best to keep all the songs for each album in one folder like:
/music/carly_simon-hello_big_man/ *.flac
NOT
/music/carly_simon/hello_big_man/*.flac
2. Toward the bottom of the mpd.conf file, you will find the Audio Output section. We are only concerned with ALSA output. The code below shows the “modified mpd.conf” file, carefully compare it to the default mpd.conf file in your text editor to see the differences.
# An example of an ALSA output:
#
audio_output {
type"alsa"
name"My ALSA Device"
device"hw:0,1"# optional
#format"44100:16:2"# optional
#mixer_device"default"# optional
#mixer_control"PCM"# optional
#mixer_index"0"# optional
}
#
3. You must ADD four extra “#” marks as shown above. This disables those features and allows bit perfect digital output.
4. In addition, make the change to the line beginning with "device" to add your correct “hw:x,x” device. You can find your digital device's output setting using the command “aplay -l” in a terminal window ( lower case “L” and omit quotations marks in command).
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OPTION 4:
And finally from www.webup8.org, http://www.webupd8.org/2010/03/how-to-switch-to-alsa-or-oss-instead-of.html
you can try: gconf-editor. In a terminal type: sudo gconf-editor
Navigate to /system/gstreamer/0.10/default and change the "audiosink" and "musicaudiosink" to "alsasink" or "osssink", depending on what you want to use. I for one used OSS ("osssink" - notice there are 3 s) because it simply works, even though it's deprecated.
If you want to do this via command line, all you have to do is paste this in a terminal:
gconftool-2 --type string --set /system/gstreamer/0.10/default/audiosink "osssink"
gconftool-2 --type string --set /system/gstreamer/0.10/default/musicaudiosink "osssink"
The above 2 commands set GStreamer to use OSS for audio and video players. To use ALSA instead of OSS, simply replace "osssink" with "alsasink" in both commands above.
If you want to use ALSA or OSS for Audio/Video Conferencing too, also run the following command (remember, the app must be using GStreamer):
gconftool-2 --type string --set /system/gstreamer/0.10/default/chataudiosink "osssink"
To use ALSA, simply replace "osssink" with "alsasink" in the command above.
Then restart your music player or video player (Rhythmbox, Totem, etc.).
To reset these values to default, run this in a terminal:
gconftool-2 --type string --set /system/gstreamer/0.10/default/audiosink "autoaudiosink"
gconftool-2 --type string --set /system/gstreamer/0.10/default/musicaudiosink "autoaudiosink"
