my former speakers, Energy 22 Pro, would go down to around 22 Hz at 75 dB SPL, but when playing loud, i would miss nearly an octave in the lows because of the box and speaker size, among other things. they could not keep up at higher power levels.
my current speakers, M80's because of box/speaker size and tuning, go lower down than the Energy when playing loud.
Frequency Response is one thing, but there is another very important thing: power response (Freq. Resp. at high power levels).
Dakkon is not the only one rambling; sometimes it's nice to be able to do that. ;-)