You will notice that the Revo is still being silent when you first install Ubuntu but this is easy to fix, go to System → Preferences → Sound, click on the Hardware tab. Under Profile select "Digital Stereo (HDMI) Output + Analog Stereo Input" to make sure all sound goes through the HDMI socket. If you want to use the headphone socket instead select “Analog Stereo Output". We still have to do one slight tweak though. In a terminal d enter alsamixer and you should find that “NVIDIA MCP7A HDMI” is showing as the chip. Press the right arrow until an entry named “IEC958 1” is highlighted and make sure it is not muted (it will have “MM” displayed above it). If it is press “m” to unmute it. Press Escape to leave alsamixer. If you try the sound tests under Sound → Preferences → Sound you should find that they now work.