Comment 13 for bug 1551385

The problem of this "solution" is that is temporary, because on each boot you need to set manually the output on alsamixer (because pulseaudio can't change it)

The driver developer Clemens Ladisch said me that it's because of a difference between the name of the output purposed by the driver and the name that pulseaudio search.

The driver said "Multichannel", but PulseAudio search about "Speakers", so he didn't found the right output.
This bug is because the output was renamed in the driver.

A simple name update in pulseaudio will fix the problem normally.

And for the workarround, thanks Clemens Ladisch :)