Maybe its too late to answer but try this if you haven't sorted this already:
Control Panel, Sounds and audio devices, Volume Tab, Advance -> Select your speaker type. Unless this is done, your speakers will only work in Desktop Speakers mode which I believe is 2 channel.
Also you have to figure out the connectivity to Live card and connection of speakers to the center (volume control, on off, controller) unit of the speaker system. I have a Korean made set of speakers which came with a Korean only manual. I struggled to figure it out and in the end went brute force.
No regrets about Live Card / 5.1 speaker set. Feels like a theatre at home with BS Player / DFX Plugin.
Stone walls do not a prison make,
Nor iron bars a cage;
Minds innocent and quiet take
That for an hermitage;
If I have freedom in my love,
And in my soul am free,
Angels alone that soar above
Enjoy such liberty. - Richard Lovelace