A fantastic product, JDSLabs make some great CMoys, and the bass boost is fantastic from my point of view. Some may argue it is a bit muddy at higher volumes, but I rarely noticed it to an extreme extent, and even when I noticed it a bit, I remembered how cheap the amp was (also, never forget you can turn off the bass boost). If you don't like the "hipster-ish" look of it, or don't trust the enclosure, I know tons of people bought $10 enclosures and fit them in just fine. I'd recommend this in a heartbeat.
 
Notes: Used with DT770 Pro 250 Ohm

Fantastic product for doing what it is supposed to. For those who do not know what its purpose is; it is meant to skip the iPod/iPhone's internal Headphone AMP so you can use your external AMP to the best of it's ability. I used it with JDSLabs CMoyBB to my DT770Pro 250ohm and did see a reasonable difference. 
 
I would recommend for i-device users who want to get proper amping.