gasolin said:
what music do you play with frequencys down to 24 hz and with enough level so it's possible to hear it ?
That question is best answered by you comparing speakers that are pretty flat down to 20 hz with speakers that start rolling off at 40 hz (or 50 or 60 or 80 hz or whatever).
The full range speakers will give you grizzly bear / barrel chested authority. On just about everything.
They will also put a considerable amount of energy into the fabric of your home, even at low volumes - on just about every pop, rock, jazz, full orchestral album you have. At higher volumes you'll be worried about cracking plaster ceilings.