Low volume bookshelf spkrs that go from 20 to 20k?

A 20hz soundwave is 27.5 feet long. It simple can't be achieved in a small room though

Good point...the long waves can be achieved but modal issues will be absolutely huge....a central position in a 14 foot room will be 7 feet from a wall and therefore reflections will be 14 feet behind the primary signal or a half wavelength off.... leading to large nulls followed by large bumps at the listening position as you go up in extreme LF frequencies...extremely bumpy. A rectangular not square shaped room and a listening position 38% from rear or back wall will help.

It might be better not to bother to produce these extremes (if it is for a bedroom music system), concentrate on something with a good mid range, small and elegant...with nice vocals and dynamics, IMHO...

Here is another suggestion for something small

SCM10-2

>A 20hz soundwave is 27.5 feet long. It simple can't be achieved in a small room though the apparent bass can be very good in a properly treated room.

At 1130 feet/second a 20Hz wave is 56.5 feet long although this is not relevant. If we were unable to hear sound waves longer than the space that contained them, we couldn't go below 12KHz when using earphones in our inch-long canals.

A pressure source (conventional box speaker) in an infinitely rigid sealed space experiences a gain of 12dB/octave below the fundamental resonance with a frequency of 1130 feet/second / 2 / the longest dimension (in feet).

This can be good : 12dB/octave nicely complements a sealed speaker's roll-off. The original poster should be able to achieve flat bass with a sealed speaker that has a 40Hz resonance frequency.

Or it can be bad. A flat sub-woofer in a car is going to be very bloated.

Velocity sources (Dipoles, cardioids) work in small spaces too.

Narrod: A 20hz soundwave is 27.5 feet long. It simple can't be achieved in a small room though the apparent bass can be very good in a properly treated room.

How are headphones able to achieve low frequencies?

Check out the Yamaha piano craft sereies. I wanted to see if I could put together a reasonable system at Best Buy.My friend asked me to reccomend systems for them but they always balked at highend prices.
After spending a couple of weekends at Best Buy I purchased a Yamaha cd reciever and two Yamaha powered subs(you could get by with one). The sound is amazing for that price range. ($400 for the system and $250 each for the sub.)Throw in a nice set of earphones and call it a day.
Now when my friends ask for a recomendation, I can take them to the bedroom and let them audition it right on the spot.
For an uprade you could substitute the the $399/Epos mini monitors.

Thanks folks for all your advice. I auditioned monitor speakers from the following manufacturers:
Spendor (similar to the Harbeth, but lacked clarity)
Dali (great sound but price was about $ 4000)
B & W (inexpensive but did not sound right)
Paradigm studio 20 (good but perhaps too big for my room)
Harbeth - liked them, price was within my budget too.

I ended up purchasing a Harbeth PS3ES-2 similar to the LS3/5a.

Thanks again (got to get the karma right)

Vish (now registered as yogananda)