dynamic range would be the range between the smallest nuances and the loudest sound reproduced
by this by looking to your oscilloscope in foobar (or whatever) most of the amplitude of the waveform is that of the lower frequencies, which requires the most energy to be reproduced, the higher frequencies will define the crest of the waveform
so it's easy to figure out that at different frequencies a headphone will have different dynamic ranges, depending on it's frequency response and volume/loudness they are driven
that's where it gets confusing since most perceive music with higher dynamic range compression (lower dynamic range) as being/having more dynamic/dynamics
and the hi-fi "definition" of dynamics is not really strictly related to the technical definition but more to the sense of perceived energy
so if you think of dynamic driver headphones they get easily bright at higher volumes exactly because they can't keep with the full frequency range dynamics, or in simpler words preserve the amplitude difference (energy ratio) between the lowest and highest frequencies of the audio waveform being reproduced, but because of that they have more treble (high frequency) energy, therefore perceived as more dynamic
so actually lcds have a higher dynamic range and that's why they are dark sounding, well actually in hi-fi terms they have less treble energy so they are less dynamic, wait what !?!
Edited by roskodan - 12/24/13 at 5:34pm