There are many types of audio connectors.
Can you identify which one your speakers use?
Here are some of the most common...
My guess is that it is the upper left at the computer end of the cable.
And that the speaker end of the cables uses the upper right.
If this is true, then most sound cards should accomodate your needs.
Here is a typical sound card set of "ins" and "outs".
If your stereo speakers use the upper left style of jack (at the computer) then you would plug them into the green jack on the card I have displayed for you.
Does this help, or did I not understand your question?
===Question===
What do you mean by a "stand alone audio card"?