I've been using the following setup for the last few years:
- Radeon HD 6870
- Dual Monitors, each connected via DVI in my bedroom
- TV connected via HDMI in the living room
- Windows 10 64bit
I was able to play back movies on my TV without problems, with audio being transmitted via HDMI output.
Recently, I got a new monitor (which has builtin speakers and is connected via DisplayPort) that replaced the dual monitors in my office. Since I connected it, the "AMD HDMI Output" entry disappeared from my list of audio playback devices and was replaced by "AMD DP Output", leaving me with no means to get audio to the TV.
How do I get back the HDMI audio output device? I do not need DP audio since I'm still using mainboards audio card and speakers in the bedroom.
Disclaimer: English is not my first and therefore system language - sorry in case my freehand translations of system terms above are incorrect/confusing, I'll be glad to clarify.