I'm using VLC player to play a Divx file that is encoded with Dolby 5.1 AC3 audio. There is an option under settings/preferences/audio for "Headphone virtual spatialization effect", which is basically another name for Dolby Headphone, which allows surround sound to be simulated in your headphones by adjusting front and rear sounds to certain levels. Anyway, my question is, in order to use this function, should I choose "5.1" or should I choose "Stereo" under audio/audio device?