Just in case nothing of the above works - check that the issue is not with the amplifier. I eventually plugged in another computer, and still silence.

Moving the cable to a different HDMI input of the amplifier did the trick. Who knows what is wrong with "HDMI3", but I can live with that. :-)

No sound in Ubuntu except at log in
I noticed that Catholics dip their fingers in Holy Water kept mostly at the entrance to the Church and apply it on their forehead.

What is Holy Water? 

Is there any specific liquid/water for it?

What are the uses of Holy Water?
