Removed, re-installed Pulse Audio, which got the sound output working.
Sound recording using Gnome sound recorder still failed, but works OK with Audacity, so I'll settle for that.
Maybe when installing Sound recorder on a KDE system there is a missing Gnome dependency? My previous system was Ubuntu (Gnome) with KDE installed on top, so I guess there were a lot of Gnome libraries there I don't have with this pure Kubuntu system.
Fixed.
Removed, re-installed Pulse Audio, which got the sound output working.
Sound recording using Gnome sound recorder still failed, but works OK with Audacity, so I'll settle for that.
Maybe when installing Sound recorder on a KDE system there is a missing Gnome dependency? My previous system was Ubuntu (Gnome) with KDE installed on top, so I guess there were a lot of Gnome libraries there I don't have with this pure Kubuntu system.