^ So, in order to set your Heights to Large, the Mains and the Surrounds also need to be set to Large. And if you set Bass=LFE+Mains, you can set individual crossover values for each set of speakers. I’m following so far.
So now you want to connect the 2WQ sub to the Height pre-out and configure the Height speakers to have a 40Hz crossover? There could be several things wrong with this configuration. First, in order for the sub to be contributing to the overall bass response, the Heights must be receiving the full bass signal content. Is that really the case? If not, what is the sub actually going to be doing? Second, you now would have bass reproduced in all speakers as well as the sub. It has been discussed many times—double-bass rarely produces desirable bass.
To be sure that the sub receives the full bass content, why don’t you power the fronts using the UPA-700 and configure the sub in-line with those speakers? Of course, this still leaves the double-bass issue.
Another alternative would be to sell the 2WQ and get a more conventional sub. This would probably get you the best overall bass quality, if that is your objective.