I have now worked out it's def a driver conflict between what appears to be Microsoft's standard driver for audio (that comes with Windows 8 via online driver collection) and realtek or amd drivers (when you try to install either of them). Verify that the configuration is correct as shown above.
Uninstall the Realtek hardware anddrivers.Then under Device Driver you will need to select Action, then select Scan for Hardware Changes. If you have downloaded and installed updated Realtek sound drivers they will overwrite your working AMD HDMI drivers and the same problem will occur where the AMD HDMI won’t output sound to your monitor. Make sure that all other conflicting sound devices are disabled under Device Manager – Sound, as shown below: Your Device Manager should look like something like this when you have the AMD HDMI sound working : Verify that the HDMI hardware has been detected and the correct driver has been assigned to it. The system will detect the AMD HDMI Sound Card and install the correct AMD sound drivers.