Sounds like there's a problem enabling Dolby Digital/DTS in your media players through spdif.
Google and download "Media Player Classic - Home Cinema", as it's the most modular and capable computer media player.
Also, go to ac3filter.com and download ac3filter, which can be configured through MPC-HC, and you can set the options to how many channels you want.
Go to any A/V forum and upwards of 90% will tell you to use MPC - HC.
VLC is nice out of the box, but it has limited functionality, the video quality has the worst macroblocking ever (due to talking a lot of shortcuts), and is not very useful in terms of functional audio playback.