Its not just that. You'll find alot of heaphone, it depends on the technology provided in them too, like Turbo boosters, etc.
Its also the player your using. Some have different power outages for headphones, and so you need to look at the Ohm's. The amount of volume/power you'll receive.
My dads set for example, must have a really high Ohm rating, because their terrible on my Zen Vision M. Sound sounds distant, and hardly no bass at all.
Though, they are really really good on stereo amplifiers with no limits, etc of power.
So, if you are looking for full size ones for portable players, be careful which ones you choose. Look at reviews first.
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