Thanks for that Ian.

First, are you sure I do not have to worry about warping woofers, can you please explain the advantages over rubber.

Second, I would rather stay away from bookshelfs because of stands and children, but what would I be sacrificing if I chose the 40s over the 50s? Should I spend less on a receiver to get the 50s or would the 40s be acceptable, but sufficient. I see you are recommending the dual woofers over the single.

Thanks again Ian,
Mark