Looking at the scenario of yours I think that there is some issue with the Pulse Audio. Well that is I think in the UserSpace. From your description I think that the card is recognized but is not being used. The problem is definitely in the userspace and precisely in the Pulse Audio volume control. I would suggest you to have the reinstallation of the Pulse and see if the reinstallation does the trick here. For doing that here is the code that can assist you a bit:
Code:
$ sudo apt-get purge pulseaudio && sudo apt-get install pulseaudio
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