Just got this amp and headphones in the mail today. I've never used a headphone amp for my iPod until now, and I'm really impressed with the improvement over not having an amp on day 1. It doesn't take the place of the home system, but it's actually for the first time a satisfying portable listening experience.
I decided on the Fiio E12 "Mont Blanc" after looking for a reasonably cheap amp with crossfeed. The HF5s replace ER4Ps that my wife borrowed for use at the gym, until they failed, and the custom molds are from Westone, made from their "Otoblast" silicone. The HF5 and ER4P both fit the same insert.
Compared to the iPod alone the sound is clearer, smoother, and more realistically punchy. I'm not going to say it's high end, but I'm for the price I won't complain. I was worried hauling around another component wouldn't be worth it. It's totally worth it.
