Woohoo !!!
My sounds problems are solved by applying a patch to alsa.
See:
-
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2104
-
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2378 (the patch)
Thanks all for helping me, especially the unfatiguable pithball, Nigel and
of course I have to look up the name of the guy who wrote that patch ;)
JeeBee.