If I understand you correctly, you don't want to use the crossover knob on the back of the sub, your receivers bass management will control the crossover of all speakers, and route the LFE below the crossover frequency to the sub.
So, on the subs crossover knob you want to put it at the highest setting if there is no "bypass" option like some of the Axiom subs. Then you will set your speakers to small in the receiver, or Audyssey should do that, with an 80hz crossover for most situations. Audyssey may change some of those settings based on the speakers it senses.
What sub did you get?
