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


Also what bass driver or drivers do they use?

Thanks.
128x128mapman
I've heard Mani's and liked those very much.   I recall they had a unique bass driver design.
PMC's, which have a transmission line enclosure, can produce more bass for their size than other designs. 
Transmission line makes a speaker larger.

The cabinet on Barefoot MM27 is Cabinet: 20.5 x 9.5 x 15.5 inches (521 x 241 x 394 mm)
Overall: 20.5 x 10.5 x 17.4 inches (521 x 267 x 442 mm)

it is flat to 30Hz and will play louder more cleanly than 99% of what people have here.
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.