I seem to have borked the sound on my motherboard, any ideas?

I have a Gigabyte H370 HD3 mobo, worked perfectly up until last night... Computer would not shutdown, so I held down the power button. Now macOS (and Windows) show no audio device except HDMI monitor :-(

I have moved the analog speaker cable to the HDMI analog out port to get temporary sound... but I am at a loss to what happened. Looks like I may be stuck with this... or USB sound card - which is a shame, as analog out (and headphone port) worked great. Looks like I shorted-out just the sound circuitry.

As an added annoyance, no OS actually shuts down correctly anymore Any help or advice would be greatly appreciated.

PS. I may have a PCIEx1 or PCIE slot available for add-in sound card? Anyone know compatible models?