I have done a bit of research on the net and came across this:
Intel Next Unit of Computing (NUC) DN2820FYKH - Celeron/Bay Trail SFF HTPC | Missing Remote
According to this article dated 30th April 2014, "...HD audio bit streaming works on Linux.It does not on Window though, most likely as an artifact of how Intel structures protected audio playback on the OS, where the Management Engine (ME) is required, but unfortunately the driver will not install".
I have read issues of this on the forum but thought this was to do with windows 8 not windows 7. So is this a general windows issue?