On my Notebook (with Realtek ALC269VB) the sound over speakers works well until I plugin the headphones, Speakes get muted as expected but no sound on headphones. I noticed that as soon as I plugin the headphones, Alsamixer, Ubuntu Sound Control and pavucontrol switched to 'Headphones' which have no effect (does not really exist). When I switch back to 'Speakers' everything is fine; I can control the sound of headphones. This is a kind of work-around (starting pavucontrol to switch from Headphones to Speakers) but not relly satisfying.
You may notice that Alsamixer says 'Intel Cougarpoint HDMI' instead of 'Intel HDA Realtec ALC269VB' what it did two days ago. Anyway, I couldn't find any differences between it.
In order to easy the work-around: is there a command line option to switch to 'Speakers'?