[Otto]

Not sure about the loopback thing. Have you been able to get a sound out of the soundcard to the receiver yet? If so, that's on indication that you are generating sounds. If you can clap and read a sound on REW, then you can receive sounds. You need those two pieces to do a soundcard cal. How do you have the soundcard hooked to itself? It should be a stereo to stereo 1/8" cable, going from the output to the input (in your case, probably "L/R front out" to "line-in"). Are volumes up all the way on the audio control for Windows?

I guess you could connect directly to the BFD, but most go straight to the receiver, which will feed the sub. I've always gone that direction.