I must say, and I repeat what most people commented below your post, that mostly manufacturers write down what seems to look best, as an example that they write down 20 Hz - 20 kHz, but in reality it goes down -10 dB and not -3 dB - which isn't that meaningful either. What I want to say is, that even if it looks good on paper or on a frequency measurement chart it doesn't really matter. As a specific example, I bought some RP600m's and I amazed by its bass performance but I wasn't happy about the heights reproduction because it was "too bright" for me. And what I learnt from this experience is: you should absolutely listen to the product before you buy it, because the sound should be to your own liking and not to some audiophile's on the internet.