Okay, both the amazon.com description and the AKG website say that these headphones are suitable/ loud enough for portable players like iPods and iPhones. THIS IS WRONG! You can get solid volume when turned up all the way, in the silence of your home. But that's it. These headphones, although not a good solution for portable players, offer fantastic sound quality, with great instrument separation. The bass is lesser than many headphones, but that's a matter of personal preference. Anyway, these headphones are simply not loud enough and their shape and size is not ideal for bringing them places. Also, the on ear version (the ones I'm reviewing) clamp pretty seriously on your head after about half an hour of listening. However, after you break in the awesome velvet ear pads, the clamping force isn't nearly as bad and they become extremely comfy.
Also, this review was about using UNAMPED porable players.
All in all, great headphones, just not for an un amped iPod.