If the content does not have 5.1 then it's likely to be stereo. Some folk work so hard to do this then discover all their tunes are stereo.
As to VLC, same issue. You can't get 5.1 if the content doesn't have it.
Receivers? Onkyo is always a name to check. http://reviews.cnet.com/2719-7612_7-269-3.html has updated reviews and top 5, etc.