23rd march 2015

Realtek sound was working fine - configured as stereo or quad or 5.1 surround

Updated to latest technical preview today - which appeared to be a full install

Now I can only configure sound as stereo or quadraphonic

If I try to set as 5.1 surround with subwoofer and try to play a test tone I get an error box saying

Failed to play test tone

I have downloaded and installed the latest Realtek drivers

I have removed and re-installed drivers and devices

Nothing works?