Haha thanks a ton, when it comes to frequency response what are some things I should consider? Like for example if the frequency is 14 to 22000 hz, would it be even better if the 14 was lower and the 22k was higher?
The human audible range is 20 Hz - 20,000 Hz, so essentially anything higher or lower than that isn't really audible. Basically since the 333D has a 14 - 22000 Hz range it presumably has a slightly deeper low end than the 323Ds that have a range of 15 - 23000 Hz, even though it's not "heard" it can still be "felt" when you listen with them.
However, frequency response doesn't necessarily describe how good a set of headphones sound, that depends on various other things.
Sorry, that's kind of a crappy explanation lol.