With each build of the technical preview of Windows 10 the audio connection from my monitor w/ built in speakers and GPU (280X) is no longer recognized to select under playback devices for sound. Seems like the audio driver is just removed and/or not recognized.
The only fix I have found for this is completely uninstalling the catalyst driver (can still find it under display adaptors in Device Mgr) and reinstalling. But after that if I restart, put to sleep/hibernate my PC - the driver audio is gone again.
The Windows team hasn't been able to provide a solution for this - maybe one of you can.