I've never done a review before on here, but I thought I'd make my own quick review just for fun.
First off, the packaging was very nice; just pointing that out.
Came with accessories and everything, however I have one complaint and that is that the line out cable it came out is pretty bad for plugging into a desktop (Mac) computer since it's so short.
I have it on a little stand though, so it's okay now - but I would have preferred a longer cable.
Now onto the main thing - the sound:
WOW, what an improvement over not using an amp originally.
I honestly was disappointed when I first got the DT990 (as a step up from my Superlux HD681s)
They sounded good, but something about them felt very muted -- so I obviously needed an amp, but I didn't have any money (until now).
Everything sounds so much more improved and refined.
Highs are higher without being piercing and so much more refined. (before they were messy and unrefined) MUCH more detail across the board in terms of highs, mids, and lows.
Mids don't sound dead anymore. They could still be considered recessed to some, but they're perfect now that I have the E12.
Lows are punchy, not as flobby sounding and again; it feels very alive (along with everything)
As for the bass boost: While I'm not a fan of the bass boost in most of my music (I have Version 2) it definitely does a good job.
One album I did like the bass boost with actually was Reign In Blood (Slayer).
The bass already sounded a lot more punchy (just listen to Raining Blood) but with the bass boost it sounded a lot more intense.
Not the biggest fan of the crossfeed, but it's nice to have and I can see some people liking it.
I tried it with some songs from The Beatles (Stereo) and it just made it sound dead, I don't see myself using it.
Even if it annoying to hear (for instance) drums on the left side and vocals on the right side, I'm used to it.
Also, I never noticed any noise except once when I hooked the amp up to my PC.
Not sure if it was the PC or just a coincidence? The volume was pretty loud.
Also, while I like the highs a lot and they're a million times better; they are a BIT too bright sometimes. However, I'd blame that more on the songs themselves (due to poor mixing/mastering/the Loudness War)
Stuff like early Metallica sounds incredible.
Before "For Whom The Bell Tolls" (Ride The Lightning) sounded dead, boring and I almost didn't want to listen to the song/album.
Now with the E12 it sounds so alive, the guitars rip and Lars' drums sound fantastic.
Hip-Hop sounds great too, drums a lot more snappy, bass tighter and vocals (this goes for every genre) have a bigger presence.
Also, one of the best sounding songs yet with the E12 that I heard is "Limit To Your Love" by James Blake (along with the whole album "James Blake")
Vocals sound beautiful, the insane bass in that one part is incredible (it sounds like my headphones are going to explode though with the bass boost on though, LOL) and the last two minutes is just amazing with so many details and sounds going on.
Really everything sounds amazing, but there are certain songs that make me go "Wow" and this was one of them.
I also recommend listening to "Sea Change" (MFSL version) by Beck, that album sounded incredible without the amp and it's HEAVENLY with the E12.
One album I noticed a great improvement upon was By The Way (Red Hot Chili Peppers)
The album has a very (intended) harsh, loud sound. It's not as bad as Californication though which I'm sure at least one of you know of because of the sound.
Before when I listened to this album without the amp; a lot of vocals sounded distorted and everything sounded messy.
It still has a fairly distorted, messy sound with the FiiO, but everything sounds SO much more tighter and great.
It's a bit weird, actually -- for instance:
The song 'Dosed' has a lot of distortion in the vocals (chorus) with the DT990 unamped, but with the E12 I noticed it's gone/not there as much and instead it has this interesting sound where it's a mix between distortion and clean punchiness/tightness.
It may sound bad to some of you, but it's personally an effect that I like with the album.
I'm against the loudness war, and do prefer dynamic music.
But, I'm not against artistic uses of it - which, was definitely present in the album since it was intended to have a explosive, Lo-Fi sound.
(Unlike Stadium Arcadium and I'm With You which are just clipped disasters)
Blood Sugar Sex Magik sounds incredible too.
'Give It Away' has these "boing" sounding effects in the background and before I had to struggle to hear them, but now; while they're not vital to the song - it definitely adds a new and better presence since I can hear things like that in my music. (going back to "Limit To Your Love")
Sir Psycho Sexy sounds sexier than ever, Funky Monks sounds funkier than ever (great joke) and Under The Bridge feels so much more powerful -- especially in the last minute or two.
It may sound like I'm over-exaggerating but I'm really not, the E12 is incredible and sounds like it could be at least 200$. (I got mine for 140-150ish)
Anyway, I went on a bit there, but you get the point.
the E12 is a great amp and is highly recommended, especially if you have a DT990 -- they go together like bread and butter to my ears.