Michael, I think Jason's suggestion is good, as are your observations about nulls. You might try a inverse sub crawl; leave the sub doing something relevant where it is and walk around - even to the adjoining rooms. I was very surprised to find a big peak in the kitchen when I did this. I'm sorry that I haven't been following your story very closely, but if there is a way to experiment with sub placement, I'd strongly suggest it.

bibere usque ad hilaritatem