What are the specs of a full range speaker?

Goroi- I was referring to speaker systems of any kind, not just single driver systems.

Sogood51- I like your "room lock" and "room shudder" concepts.

Newbee-The passage says "reaches down into the 30s WITH SOME WEIGHT". Is that meaningless? The meaning was clear to me but maybe it didn't translate well.

Pbb- Thanks for taking this where I had hoped it might go. What use is the inaudible? I personally feel that the whole absolute sound model steers us away from a relaxed and pleasant music listening experience and causes us to grip our chairs and squeeze the last note out of our equipment.
Why are so many of us so obsessive?

Inaudible content on the low end can be detected by the body because it shakes the floor, ceiling, walls, etc.
How would we detect inaudible high frequency content?

Shadorne-
Your response concerning room anomalies provides specifics where I previously had only general awareness about these problems. 10 to 20 db is a lot of variation. When you say that room equalization is limited to a small sweet spot I wonder if you mean a pinpoint or a zone across the room being localized front to back.
I currently own a pair of speakers that reach down only to about 38 Hz. They are sold and I'm awaiting a new pair with deep bass capability that is equalized. After reading your comments I'm very curious to see whether or not I wasted a lot of money.
Does anyone here have equalized bass in their speakers and what have you found? Also what are your room dimensions?

Dan,
The Definitions have internal amplification for the onboard subs. These have an adjustable gain control on the back of the cabinet. Zu also makes (but doesn't publicize) the Definition Pro which has heavier duty professional grade woofers and requires Bi-amplification. With this arrangement they sell you a RANE PEQ 55 digital parametric equalizer to tailor the response from 40 hz down to 16 hz. This is what I have on order. The difference in price between my old speakers and these new ones is such that I am looking for a big improvement.

Yikes. The more I read, the worse I feel. I must be jumping in the snake pit to get away from the snakes. The picture I had in my mind indicated much smoother sailing than what you guys are proposing. Maybe I'll get lucky about the bass in my room. It's pretty good now with an outboard sub (also ZU) but there are definitely places in the room where the bass is more pronounced. It's especially good at my desk down the hall in the bedroom about 50 feet away from the speakers.
There's always Zu's return policy to fall back on but this project is clearly going to cost something no matter how it plays out.