Hello crhendo
I have found the solution now.
I change the HDMI receiver input from DISPLAYPORT to HDMI out.
Deinstall graphics and audio drivers.
Install the last drivers from 5-3-2014.
Set the audio source setting from the Sony TV from GENERAL to HDMI.
And its works now.
Have audio and video on Sony tv and Yamaha receiver.
Best regards
SEAT1951