Count me as a DT1350 fan! Got a pair last month along with Audio-Technica ESW9 to choose between them for my Christmas present. With 100 hours of A - B comparison, the DT1350's won and have become my favorite headphone!
But I'm keeping both. Here's why. I find the DT1350's awesome and super precise but, as others have mentioned, they are source finicky. I listen to digital and analog, older and newer recordings, and many genres of music. I found the DT1350's sound superb with the lucky subportion of my music collection that is well recorded/engineered/balanced, and either so-so or not-so-good with lesser recordings. When they sound great, though, they're really amazing. I've had jaw-dropping moments listening at a new level of fidelity with some music I've had for ages, but never sounded so good, such as Stanley Clarke's self-titled 1971 album (especially his upright bass sound!), Jacques Loussier's Play Bach albums (50+ year-old jazz recordings), and Thom Yorke's 2008 album The Eraser (on which the track 'Black Swan' makes a demonstrative case for the super fast dynamics and deep bass extension of these cans!).
Some well-recorded hip-hop (Kanye West) and electronica (The Knife) work well. A majority of my albums and music files, however, don't pass muster in terms of source quality on the DT1350's, especially where deeper bass extension or dynamic range is lacking.
Although the ESW9's sound less precise, a bit boxy and more colored in comparison, they are nonetheless quite charming, more flattering, and way more forgiving musically with less-than-perfect sources, so they pick up the slack, especially with lossy digital audio that the DT1350's would spit up. Turns out the ESW9's work great for casual listening and don't hurt my ears (the fleshy, dangly protrusions on the sides of my head that have been getting crushed in long listening sessions by the vice-grip clamping force of the DT1350's) as much, so comfort is another plus. Both have very good midrange, which, at the end of the day, is where I focus most of my music attention. And both work great across genres, with the AT's having the advantage on mid-bass prominent music like dub, dance and rap and for dealing with surface noise on vinyl.
For my comparison, music output has been via an iBasso D10 Cobra, Minibox-D, iTouch 2 (direct or analog line-level out to amp) and iPhone 5 (direct, with a FiiO E3, or digital output from Apple Airport Express by optical digital cable to iBasso D10 DAC).
I just ordered a little Digizoid ZO 2 with hopes of occasionally beefing up the low end on some of my music that lacks sub bass for the DT1350's.
As a disclaimer, I'm fickle with headphones and have had quite a few favorites as disparate as Shure SE530, Etymotic ER4 (which started me on this quest a dozen years ago), headbanded Yuin G2A, Senn 280 and cheapo Koss PortoPros.
I find the isolation of the DT1350's great. They don't insulate against airplane noise nearly as well as the SE530's--sort of apples and oranges, comparing cans and IEM's, but I'll still be taking the SE 530's for air travel and keeping the DT1350's in my laptop bag.
Also, I initially tried out the Bose AE2i circumaurals together in the audition. Though quite comfy, I sent the Bose back as it was readily apparent they weren't in the same league sonically as the very good ESW9's and excellent DT1350's.
Edited by tobor8man - 1/8/13 at 7:03am
Gone is the midrange problem without losing the bass extension and very clean treble. I predominately use these at work with an iBasso D-Zero to get the isolation and the pair with high-bit AAC or lossless is an excellent value. 
