Seems that creating a $HOME/.asoundrc file with
adding a file nvidia-hdmi.conf in /etc/modprobe.d/ with
options snd-hda-intel enable_msi=0 probe_mask=0x108
Did it! I am getting sound from every applications, even youtube and other flash sites.
When I buy a nice set of speakers, I will redo all this to use the optical output of the mainboard. Will see then!