After a LiveCD install of Intrepid there's no sound! Sigh... Ctrl-Alt-F1 to get a terminal.
Step 1 - Kill Pulse Audio & Install ALSA
Install the following packages:
% sudo apt-get install alsa-oss
% sudo apt-get install libasound2
% sudo apt-get install libasound2-plugins
% sudo apt-get install sysv-rc-conf
Move Pulse Audio (to the home folder) and then turn it off:
% sudo mv /etc/Xll/Xsession.d/70pulseaudio ~/
% gconftool-2 -s -t bool /apps/gnome_settings_daemon/plugins/sound/active
% asoundconf unset-pulseadio
Remove Pulse Audio from runlevel:
% sudo sysv-rc-conf
(page down until you find "pulseaudio" then uncheck all the boxes, save and exit)
Configure ALSA to use your sound card:
% asoundconf list
Names of available sound cards:
% asoundconf set-default-card [card name]
And ensure that libao.conf is using ALSA:
% sudo nano /etc/liabo.conf
Step 2 - Install nVidia & ALSA Drivers
First, kill the GUI (you can restart it using gdm):
% sudo /etc/init.d/gdm stop
Uninstall the proprietary drivers if you installed them (Ubuntu will probably recommend you get proprietary driver version 173 or 177 when you first install).
% sudo apt-get remove nvidia-glx
Now download the latest nVidia drivers from here (I'm using Linux IA32 version 177.82) and install:
% sudo sh [NVIDIA-Linux-x86-177.82.pkg1.run]
(Follow the prompts... Yes, Agree, OK, Next, Yes)
Reboot the computer and download the latest ALSA drivers from here (I'm using "alsa-driver-1.0.18a.tar.bz2"). You'll then need to decompress the file, go to the directory it creates and install:
% bunzip2 -c [alsa-driver-1.0.18a.tar.bz2]
% cd [~/directory name]
% sudo make install
Reboot the computer again, then see what you have:
% aplay -l
Hopefully you have a device with "HDMI" in it. If not, try looking here.
Now navigate to System->Preferences->Sound and turn everything from "auto-detect" to the HDMI device (and disable ESD if it is enabled).
Open up the volume control (double click on the speaker icon or gnome-volume-control) and change "Device" to the HDMI device.
Then select "Preferences" and check anything with "IEC958" in it (also, in "Playback" make sure the IEC958 device is not muted!)