Same happened to me, sound used to work ok on a previous 1204 release, I logically have no hdmi audio anymore . I have a zotac zbox.
Here is my video card info, probably is not listed and thats why is not detected during the boot up
root@moon159:~# lspci -nnk | grep VGA -A3
03:00.0 VGA compatible controller : NVIDIA Corporation GT218 [ION] [10de:0a64] (rev a2)
Subsystem: ZOTAC International (MCO) Ltd. Device [19da:3100]
Kernel driver in use: nouveau
Kernel modules: nouveau, nvidiafb