I'm guessing the problem is that my motherboard is very recent; it's a Gigabyte GA-Z170X-Gaming 7 using the new Z170 (Skylake) chipset.
The output of
lspci -v shows two "Audio device" blocks, but I was thinking one of them might be for my integrated graphics HDMI, and the other for my graphics card (Nvidia GTX 980 Ti) HDMI:
00:1f.3 Audio device: Intel Corporation Device a170 (rev 31) Subsystem: Gigabyte Technology Co., Ltd Device a036 Flags: bus master, fast devsel, latency 32, IRQ 16 Memory at da140000 (64-bit, non-prefetchable) [size=16K] Memory at da120000 (64-bit, non-prefetchable) [size=64K] Capabilities: <access denied> Kernel driver in use: snd_hda_intel 01:00.1 Audio device: NVIDIA Corporation Device 0fb0 (rev a1) Subsystem: Gigabyte Technology Co., Ltd Device 36b7 Flags: bus master, fast devsel, latency 0, IRQ 17 Memory at dc080000 (32-bit, non-prefetchable) [size=16K] Capabilities: <access denied> Kernel driver in use: snd_hda_intel
This similar questioner on 15.04 resolved their issue by installing an ALSA daily build. I tried that but nothing changed. Wondering if it's because I'm on 14.04 which probably has an older kernel. Should my next step be updating the kernel?