What are the specs of a full range speaker?

Stereophile ranks (in thier component recommendtions) speakers as full range if they are relatively flat from 20hz to 20khz. They have a second category for those that do not which includes speakers which have a 30hz to 20hz response. At least they did when I subscribed some years ago.

However I agree with Sogood51, a speaker which is spec'd out as flat to 30 hz produces a lot of bass and you may not miss that last part of an octave much.

A speaker which "reaches down into the 30's" is sort of a meaningless description. What is important is the rate of fall off when it hits its lowest 'flat' output. For example - flat to 60hz could still have some minimal output in the 30's but it would have little impact on the sound, whereas a speaker which is flat to 45hz might well have, depending on the speaker/cabinet design, a -3db frequency response of 35hz +/- which could be quite respectible, depending on the size and dimensions of your room.

Muralman1, I agree, and then some.

The real thing is the only thing! No audio system will ever come close, not by a great margin, to ever reproducing the dynamics and power of a grand piano. Anyone who thinks otherwise hasn't been listening to much live piano music, in the home or concert halls. And it ain't just the sub 30's either. JMHO of course. :-)

Muralman1, I can't dispute what you've heard. Certainly I've not duplicated your experience. FWIW, and not a real comparison, but I'm sure you've heard a stereo system playing 'upstairs'. For those of us who have lived in flats or apartments/condo's etc, that would be common. Well when I lived in a flat in SF the upstairs unit had a grand piano - it never, ever, sounded like a stereo system. Especially transmitted thru the floor above. You knew what it was instantly - there is a whole lot of 'vibrations' going on with a live piano at all frequencies that just seem to elude (most?) audio systems abilities to reproduce with the same degree of dynamics as a live piano.
BTW I assume you meant by 'in the distance' that the sound seemed a bit compressed as compared to 'live' and that certainly would be one of my points of comparison. :-)

Macrojack, FWIW, as I have no experience with Zu's, what Zu is offering is probably an excellent solution to providing really deep bass in a meaningful way. A parametric equalizer will go a long way towards solving speaker and room integration.

However (and you knew there was a however coming :-)) whether your room can support this type of bass is one issue and whether your sources/components can withstand the distortions that the additional sound pressure created by this kind of bass can produce is another.

A third issue to consider is that typically an equalizer can be very effective in lopping off the peaks of nodes but isn't nearly as effective in raising the level of the nulls to 'flat' without doing some damage to the sounds of the neighboring frequencies and soaking up a lot of the power available from the amp. That is usually determined by the design of the equalizer, the amount of correction needed and the power available from the amp.

Have you mapped out your room and determined its nodes and nulls and how they will effect the sound at the listening position and where the speakers will be positioned for best sonic results considering the upper frequencies which are determinitive of things like sound staging, balance, and good tonal integration? There frequently is a fair amount of difference between good bass requirements and the requirements of the upper frequencies. Most folks end up with some sort of compromise.

If you haven't worked all this out in advance don't be surprised if you not only don't get a 'big improvement' - you might not even break even.

JMHO - YMMV.