John, you haven't given a key piece of information: what if any bass management your pre-amp or receiver has. Typical HT receivers using the sub output cross over to the sub below about 80-90hz. In that case, the crossover in the sub shouldn't be used at all; you set your VTF-2 to bypass it completely. I assume that you mean that you've set the VTF-2 crossover(nominally 30-90hz)about half way, but note that sub crossover markings are often inaccurate and you may not actually be getting 60hz. If you actually are getting an "open spot", you can try setting the VTF-2 cross a little higher, but you should describe your sub hookup in more detail.
