Got a shock tonight when I booted up my computer from cold. I got sound. From my HDMI output to telly port. Via my R9 390X. This happens so rarely it's a surprise, as I usually have to re-install the sound drivers from scratch every time I start up. And this only happened on Windows 10, as AMD, Realtek and Microsoft hate each other and me and won't usually play nice with each other. And me.