I just loaded up a D34010wyk with Win 7. latest drivers and Bios. HDMI 1.4 cable to my Samsung UN60EH6050F TV. Optical from the TV to my Yamaha receiver. (no hdmi on my receiver)
under sound / devices. the only choice is 2 channel stereo. there's no option to change to 5.1. There are other posts with the same issue.
You may need to connect the Intel® NUC to the AVR first and then this last one to the TV.
I suggest you continue in the older discussion where you already posted.