Didn't they used to talk about having a speaker directly overhead the listening area called the God channel or something? Brief searching is yielding no results. I'm just surprised that a speaker directly above you wouldn't be of more value for all of the planes passing overhead and what not. Maybe the effect is accomplished well enough with the existing channels. In any case, I like the idea of a full-range speaker mounted directly above me which could fall at any time. In the event it falls, JohnK might take it as a sign it's time to upgrade my body.
