[grn1969c10]

no they're 1/4 inch jack outs adapted into phono

What kind of sound card do you have? I am wondering if you are trying to use both the left and right soundcard outputs to drive both sides of your stereo amp. As bruce said, you will need to use the right side line out from your soundcard and then use a splitter to split it into left and right amp inputs.

to run through an amp

If you feed the amp directly, you may not see the effect of the receivers EQ or crossover which would normally influence the output.