Back when I had Bose 701 towers (don't dismiss me yet, I upgraded to Mirage OM-5 through a trade in program at Tweeter) I was looking for a sub to give more punch down low. I was looking at the same sub you are, the Sunfire Signature. I had wanted the sunfire to handle the lowest bass and the 701s to handle the rest. The dealer from Sound Forum said the best route would be to go from the sub preamp out to the sub and then to the 701. This run would have required 2 25-30' cables to do, the dealer knew this by the way.