But for those of you who also want to listen on high-end audiophile or studio headphones, it’s about more than just storage and file compatibility. It’s also about more than just having a headphone jack. You want the internal amplifier to be powerful enough to drive your headphones, as many high-fidelity models aren’t necessarily made with portable media players in mind—they’re often designed to be used with more powerful home stereo or studio/recording gear, and have much higher impedance. This means the relatively low-power jacks on smartphones can’t coax much sound out of these headphones, because they’re expecting much more power to drive the signal. Even some of the most audiophile-friendly portable media players might not have quite enough amplifier power to work well with high-impedance headphones, so make sure to check the specs (although you’re safe with the two models listed above).