It's a good little volume boost for harder to drive cans since it's frequency response is almost flat.

I love mine. Still not sure whether or not it's a fake as I got very conflicting feedback from FiiO. But used for my gym rig it definitely makes my music fun.

These are not good for your Iphone and also not worth $35.00 that they are selling on amazon. There is a review of them on lifehacker and are not recommended for Iphone or Itouch. You wont notice much of a difference.

@Frankrizzo- On an Ipod touch with an LOD, it cuts the output impedance from about 7.5ohms to .25, which can make a difference in lower impedance headphones, and its nice to have since my Ipod can't drive my Q701s or HD428s loud enough without an amp

I used them for my iPod and there was a huge difference. That said, I'm never content and always upgrading. I just got the E17 and it is fantastic.