FOUND the FIX.
My Issue:
OpengGL drivers worked for vid. BUT hdmi Audio not available. Due to it being disabled in kernel.
Suggested fixes:
1] use ATI prop drivers.
Result: Didn't work. Crashed my Unity. (even with couple diff versions of drivers including beta).
2]Enable the ATI audio in kernel using grub so it can be used with OpenGL.
Result:This didn't work either. eventhough I can see that the paramerter is being passed.
3] upgrade Kernel to latest or 1.13 or newer.
EUREKA. This worked. I upgraded to 3.14 (latest stable in mainline). No need to prop ati drivers. OpenGL works as the audio has been enabled in 13.3.