What are the smallest speakers that are clean and flat down to 20hz?

^interesting yes, but if I'm missing something please point it out to me; where are the specs, measurements, tolerances? Without which, I don't think they can qualify. 

http://www.stereophile.com/content/thiel-cs35-loudspeaker-specifications#4SSuUmxSowLoD8Ce.97
?

I thought the OP criterion was clean and flat to 20 Hz?
Perhaps he can specify what flat is to him: +/- dB ?
If the recording can contain it, and my room can contain it, I want my system to deliver it.

^That's why speakers should be anechoic spec'd. It gives us a standard neutral base line. Now you just need to provide us with your specific criterion, so the equation can be completed.   +/- 3 dB seems to be fairly standard, though better is well, better. :-)

I think "Plays flat to 16 Hz. " might be a bit generous:
http://www.stereophile.com/content/goldenear-technology-triton-two-loudspeaker-measurements#XYlmKGoz...

I think we have a winner!
Incredible!

^With those dispersion characteristics, and everything else; is the ideal surround sound speaker?