Let me first say that I like the E5. But I think some here don't really understand what it is. Although the spec sheet says it can drive any headphones up to 300 ohms, that's just not true. It's not that powerful. What the E5 does well is clear up relatively easy to drive 'phones. What it does really really well is provide a nice bass boost for a lot of easy to drive open phones that are very popular around here: AD700, lower end Grados, etc. What it does very very very well is portability. If you're like me and the sight of some "portable amps" that are bigger than my already too big 6th gen iPod makes you cringe, then this is the amp for you. I find it actually quite convenient because, when attached via my LOD, I can just shove my iPod in my pocket, clip the FiiO E5 to the outside of my pocket and then I have my volume control right there. Since I'm not that big on skipping songs, I prefer to just let shuffle ride or listen to whole albums, its perfect for me.
With my Grado SR60i's, the bass boost stays on most of the time. They honestly don't sound much different, if at all, with the FiiO on if the bass boost isn't activated. I think this is more of a testament to how easy they are to drive than it is to the E5. With my Denon AH D1001's the bass boost generally stays off. However, with these I find that the D1001's are "cleaned up" quite a bit with the E5. The bass, while just as punchy as ever, is much tighter. Anybody who is familiar with the D1001's will tell you that while they are a fun can, they're not the most detailed. But much of that is alleviated with the E5. And its fun to have the bass boost there when something like Nelly's E.I. comes on.
It's weird, I'd say that the SR60i and D1001 are pretty different, but complimentary 'phones unamped. However, with the FiiO and the bass boost activated with the SR60i's and off on the D1001's, they are actually very similar headphones. The SR60i's are still more detailed, forward and aggressive and the D1001's are still "fuller" sounding, but the difference is probably cut in half.
All in all, I'd say the E5 is a great value. When its criticized as nothing more than a bass boost circuit, I'd say that for harder to drive phones, that is probably the case. Just for kicks I tried them with a set of HD600's and my LOD out of my iPod. The E5 didn't really cut it there. Although that could be just as much being used to the sound of the HD600's out of an $8000 soundboard as it was the E5 being underpowered for the HD600's.
But pair this baby with an iPod, a LOD cable and some easy to drive headphones and you'll learn the beauty of full volume output out of your iPod. And the E5 is a cleaner attenuation circuit than the iPod's headphone jack is, by far. This is what people are mostly talking about when they say the E5 really tightened up their 'phones, I believe. You're getting closer to bit-perfect output out of your iPod. The FiiO does provide more headroom, I believe, which helps on hard transients and cleans up the lower registers.
Anyway, great product for $25 bucks. Enough rambling.
