Well I have an SBLive card w/ a digital connection, so see if this helps.
1.)Run AudioHQ, Open up the 'Mixer' utility.
2.)Click on the Environmental Audio icon (in the top right).
3.)In the newly revealed panel under the 'Speaker' section, turn Digital Output on.
4.)Hook the speakers up using the digital connection.
5.)Restart, and pray that it works!!
I suggested that because before I figured out how to enable digital audio and was using my analog connection, I wouldn't get any sound... hopefully it helps.
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"We don't need no water let the motherfucker burn... Burn motherfucker, burn."
-Bloodhound Gang, "Fire Water Burn"