you need to set levels in the VX s/w. then SF will recieve a digi signal path. i mispoke earlier. certainly you should have more than 6db of gain to play with in the mixer you describe.
i've never used the VX, but isn't there a dialog box where you make your choices?... sample rate, input source, etc? when selecting analog input, i would think a level slider would then be provided. if this is done through the mixer, then fine. if you are getting an error message saying something about using windows volume control, then you don't have the proper soundcard selected within Windows.
yes, this prolly shoulda went in the Computer Recording, but we're here now, an you didn't know what the problem was to begin with...
no big deal...
we're here to help, no matter what forum ya throw it up in... hehe...
~S