When I open mixer, I have the 2 devices, none of them muted. When I click on settings and choose Select Master Channel, I get 2 channels, Event Sound and opera:Playback Stream. No matter which I choose there is no sound. But when I open PulseAudio Volume control and I highlight High Definition Audio Controller in Phono-KDE Control Module and press the test button, In the PulseAudio screen a new stream that is not usually visible, kcmshell4, pops up. That is linked to High Definition Audio Controller. No sound though. This disapears after the test sound stops. While it is being displayed I can change the audio stream to Internal Audio and the sound will play.