Given the specs they have listed on their website (13.3 ohms, 119db sensitivity), I would think a recent iPod could probably drive them fairly well without an amp. I often use my 32-ohm/97db Grados without an amp with my iPod Classic, and you lose a little bit of bass control (and are stuck with the iPod's volume control, which is not fantastic-- one of the best reasons to use an amp with an ipod, IMHO, is to run it full out and let the analog amp attenuate the volume rather than the digital ipod), but they're quite usable. Unlike my mid-to-high impedance AKG or Sennheiser 'phones, which sound decidedly weak and not too loud on an unamplified ipod.

I wrote a review elsewhere on this site. I've owned both the UE Super.fi 5 Pros and the Triple.fi 10 Pros. Both were easily driven by my iPhone. These are IEMs (in-ear-monitors) not headphones, so make sure you understand that. They actually go into your ear canals. Earbuds just kind of sit in the entrance to the canals.

The top of the line UEs are true audiophile quality IEMs. They make universal-fit models, that anyone can use and they also make custom molded IEMs that are fit exclusively to your ears.

Dave

My Triple.fi 10 Pros sound great with my iPhone and no amp. They're not very amp-sensitive at all.

Dave