Comment 7 for bug 441746

If it's unrelated to this issue which now seems resolved, you need to file new bug reports and check to see if an existing bug already exists as you do so. This bug however needs to be closed. You may want to post in the forums as well, but if an out-of-the-box install of 9.10 (and also try 10.04 as it may have been resolved in it) isn't working for you, that is of course noteworthy.

Just to mention one thing though, HDMI audio should show up as a separate hardware device under the Hardware tab in sound preferences. This is because it is a separate device, it's using the video card. If you have a video card with HDMI-out and you do not see any HDMI or "HD48x0" as mine is called. Also, the video card drivers may be the issue too, unless that part is separated out. All I know is I am using the ATI close source driver FGLRX and I can see both HDMI audio devices. I think the open source driver also should show them (or maybe they are unrelated like I said).

I am currently running 10.04 Lucid Lynx on a computer with a Nvidia card, a 8600 GTS, and the close source Nvidia driver. On it, HDMI audio does not show up as a device. I am not sure if this would change if I switched back to the open source Nvidia driver.

So please file a new bug if there isn't one already.

As for ALSA, it is supposed to be fully taken control of by Pulse's settings AFAIK, and that is probably why the audio controls don't work for ALSA anymore. It's just really strange that master mute is the one thing that still has an effect, even in 10.04.