I did install the actual slitaz64-rolling-core
and in it 2 users (=also an user guest)
guest ha no access to the sound and alsamixer answers " cannot open mixer: Permission denied "
it has not access to the sound icon (ok, without access to the sound, it is good so ah ah ah!)
to see which user is logged in, the only way is to open a console! it is absolutely not good...