Being a newbie to this program but having worked with Vegas and Magix Pro before, I think the following applies, based on experimenting with Cyber Director:
The True Theatre Sound option on my very expensive HIFI provides a somewhat muffled result compared to two channel stereo. The reason I speculate is, it does put the sound on all channels however adds a delay or echo to enhance this to a pseudo surround - making the sound to me less optimum (I tried mixing music videos).
As to true surround I am not sure if this can only be properly achieved in conjunction with their Audio Director365. According to their website it even manages to mark objects in Power Director and make the sound follow.
However this is only available with those features, as I understand it, if you make one of their monthly subscription schemes.
I feel a little disappointed and dazzled as I opted for Power Director BECAUSE I finally wanted to make 5.1 Videos and feel a little cheated. But maybe I am just not familiar enough with the programm, however can't find anything in their online handbook either contradicting me.