There currently is no simple or definitive answer to this question. HD audio passthrough (with the Celeron-equipped units) on NuCs / boards equipped with Intel HD Audio, is an ongoing battle with Intel driver techs. The NuC in question is a Celeron one, equipped with Intel HD Audio.
Under linux / OpenELEC, it works - given that the playback software supports it of course (Kodi / XBMC etc). The fix was introduced in kernel 3.10.xx ->, and applies to Sandy Bridge and onwards. On some linux distro's, it may require PulseAudio if this does not come pre-installed.
Under Windows (8.x +) there is currently a work-around, given that you're able to install the GFX drivers intended for one of two (to my knowledge) other units. Those drivers will work for some models, others not. Links / details can be found in the two first links given in this post:
With Windows (8.x +), there are also other requirements regarding setup and driver requirements for HD audio passthrough to work. Details on these requirements can be found at the bottom of the aobve linked post.