I agree with Timo, but I have also found that my hearing above 16kHz is quite limited, so I never worry about any HF extension above about 18kHz. On the other hand I think that the LF information (down to 20Hz and below) really helps to recreate the atmosphere of a real venue. (I bought an active sub about 2 years ago and it transformed my system).
I also agree with CDC that a two-way design cannot possibly produce real low bass without severely compromising the mid-range, since the same driver can shift air at 20Hz and also be accurately reproducing 3kHz at the same time.
I also agree with CDC that a two-way design cannot possibly produce real low bass without severely compromising the mid-range, since the same driver can shift air at 20Hz and also be accurately reproducing 3kHz at the same time.