Originally Posted by olear
According to Apple, the latest generation Classic, Touch and iPhone 4/4s all have 32 ohms.
Is 32 ohms considered a high output impedance? Or is ohms and OI two different measurements?
Is it true that iPods have high OI and poor transparency compared to a Clip+ and J3?
Impedance is a measurement, ohm is the standard unit used for measuring. 32ohm is a huge output impedance. The ideal output impedance should be 1/8 of the headphone's impedance, so with 32ohm you'd have to used something like the Beyerdynamic DT880 @ 250ohm - not ideal for portable use...
It's not 32ohms, as you can see there. It's still a bit high, but nothing obscene. The Apple earbuds have 32ohm impedance, maybe that's what you meant.
If you google "headphone amplifier output impedance" check the second link, it's a very good source of information.