I've just found the reason (at least on my laptop): the problem is with
esound package -
rover:/home/rover# ps aux | grep esd
rover 2655 0.0 0.4 2048 580 ? S 18:39 0:00
/usr/bin/esd -nobeeps
prevents alsa from working. After alsaconf there is no esd running, but
after reboot it appears again.
How to disable esd on bootup - I could not deistall the esound package
because it suggests to deinstall a gnome-desktop-environment package, and
deinstall of esound-common suggests to deinstall a lot of other packages,
that I would like to preserve as well...
Kind regards,
Vladimir.