The only way I've ever been able to control SPDIF output with any Linux distribution using alsa is by installing aumix or a variant and controlling SPDIF with the "Digital1" control.
For Ubuntu Feisty you can install aumix (a terminal based mixer) or aumix-gtk (gtk GUI). I use the gtk version. So for newbies do this: 1. Open a terminal. 2. Type "sudo apt-get install aumix-gtk" and hit enter. This will install the mixer you need. 3. Now type "aumix-gtk" and the mixer will pop up. 4. A. If you want SPDIF output enabled, set the "Digital1" slider all the way to the left (0). B. If you want SPDIF output disabled, set the "Digital1" slider all the way to the right (100). Note: There is no in between setting, this control should really just be a toggle selection of some sort. IMPORTANT NOTE: Every time you play a digital source (i.e. Dolby 5.1) and the source changes mode, for example if you're playing a DVD and the video switches from stereo previews to the Dolby Digital movie, the aumix "Digital1" slider will actually reset itself back to 100, disabling SPDIF! So you have to set it to 0 to enable SPDIF again. This is really a royal pain, and may be the cause of the mysterious loss of SPDIF some of you are experiencing. In any case, I hope this helps. I'm just a user and discovered the "secret" of Linux SPDIF output years ago, and have complained to developers many times, asking them to please fix this ridiculous and user-stopper problem, but to no avail. The Linux developers of all relevant audio software components and distributions are equally guilty by the way, I'm not singling out Ubuntu. It sure has lost Linux a lot of potential users who simply wanted to watch DVD's or Digital TV with SPDIF output though. It's really a shame. -- Alsa loses AC'97 SPDIF output in Feisty https://bugs.launchpad.net/bugs/118861 You received this bug notification because you are a member of Ubuntu Bugs, which is the bug contact for Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs