I know there have probably been about 1000 of these on there, but i figure why not one more opinion.
To start off, in case you were debating buying one of these, if you dont have an amp, BUY IT. The difference is uncanny. So i'm going to break this down into 2 categories, audio quality and portability/convenience. I'm listening to these with Shure SRH840s
1. Audio quality is amazing. I've listened to every genre i can think of with this thing in the past 2 days and it brings the music to life without a doubt. I say with confidence it brings out things in every song you've never heard before. Stuff that i've even identified while passively listening. Most of my music is 190kbps nothing lower. The bass boost on the EQ has 4 levels 0-3, you definitely DO notice a difference when using this, however its not too intensely drastic. Noticeable, but not mindblowing change between the levels. Personally ive been listening to everything on 0 or 1 if its rap/electro/dubstep. Personally i like my bass a bit tighter on my Shures, a little more controlled. Shures are NOT known for their bass impact, theyre really flat and honest, and let me say that when i listen to dubstep with these cans and the FiiO E7 i can feel the bass on my head, its meaty, healthy, clean and AWESOME! I didnt know my headphones could sound like they do until i got this little toy. The subtle things i think are what surprised me the most. Some little instruments in the background especially on Animal Collective tracks, surprised me the most. Made some songs sound like new songs. It keeps the highs, mids and bass healthy and clean with strong detail.
2. The amp itself, is small, sleek, light, and very portable. Personally when i commute to and from work, i put my ipod, or android in a bag i carry on my side and let the giant cord of my shure SRH840s sit in there so i dont have to worry about it being in my pockets and all messy. So adding this small little device is no difference to me regarding portability. However, I have traveled around with it in my pocket and it isnt much of a difference with an ipod. The E7 is just roughly the same as an Iphone, so put your ipod ontop of that and see what it looks like. Plus the device comes with a rubber band that holds the two devices together snugly. So I give this a definite YES. So if youre worrying about it being portable or inconvenient, dont.
Overall, i highly recommend this device. Before you go waste money on another set of cans, spend the 80 or 90 dollars on this and you'll feel like you bought a bunch of new gear if you DONT already own an amp. There probably are other amps out there that are much much better, just considering price and quality. However, overall, considering the price, size, portability, look, audio quality, 80 HOUR BATTERY LIFE!, this thing is hard to ignore if youre looking to spend money and are in the market for an amp.
So YES, buy this if youre in the market for a totally solid little amp to take to and from work or school.