One thing to take note of when comparing frequency response of various speakers (or anything really) is the amount of response at the extreme ends of the spectrum. A graph of the speakers' response is helpful, but rarely available. A standard designation is +/- 3 dB. It would be a fairly safe bet that the bass response will be down by 3 dB at the quoted range. If it doesn't say, assume the worst. It could be +/- 10 dB, meaning that you wouldn't get much useful output at the low end of the response range. Under those parameters, the upper end may also be down by some amount. Even if it does say +/- 3 dB or +/- 1 dB or whatever, I'm sure they do things to inflate the response. Maybe measuring in an unreasonably small listening space?

Stu