Headphone output doesn't work with NVidia MCP78 High Definition Audio Controller

[b. f.]

>I use a laptop with PC-BSD and couldn't get output over the headphone.
>The built-in speakers of the laptop work fine and keep working even
>when a headphone is plugged in (whereas on Windows they get muted). I
>tried every slider and switch in KMix, but nothing enables sound over
>the headphone.

You need to look at the sound-related dmesg output from a verbose
boot, or a boot with hw.snd.verbose=4.  Then you can look at some of
the suggestions in snd_hda(4): you may be able to get the headphones
to work by adding the appropriate device.hints(5) as described in
snd_hda(4) manpage.

b.