An estimate for the frequency range means very little without a specification for how much tolerance +/- in sound pressure level.
Different manufacturers do not even bother to tell you the premises for a given range.
And even with a very wide range it will probably not sound very good if the response inside that range looks like a rollercoaster.
Serious manufacturers will most often give you their specs for the given range, and if they do you can pretty much always bet their response will be better (more flat) inside the range. This will in most cases result in less colouring of the original sound.
This apply to speakers and headphones but also with microphones.
On the other hand we have to remember that we normally do not listen to sinus test tones. All music is sum of a rather complex chaos of sinus tones. Many sounds are made up of a wide variety of signals in a possibly wide spectrum. If a baffle is not able to produce overtones correctly this could destroy part of the total impression even though some bits of the signal is outside our "hearing range".
The only way to predict if a product is good or not is to listen to it. And remember none ears are the same, thus will all our impressions be slightly different too, so discussing what sounds good to others does not make much sense.
Sorry for my bad english. Happy shopping.
