VideoStudio :: X4 Audio Present But Not Played Back After Capturing VHS?

I've tried everything I can think of to get the audio to playback after capturing from a VHS tape, but can't figure it out. I can hear the audio output from my sound card during capture, but playback has no audio. I noticed in the Video Properties box of the Options menu in Capture that the "audio source" says "pass through to sound card", but the "audio source" box is grayed out and can't be changed. I am using an S-Video cable for the video from the VCR, and L/R audio to a stereo plug into my Line In on the motherboard. I can hear the audio during capture, but not playback. BTW, the only means I have at this point is to use Pinnacle Studio to capture, then export as an mpg. file to import into VideoStudio. Pinnacle gives me a choice in audio inputs. Why is VSX4 not allowing that?