Pros: absolute detail MONSTER, good mids, extremely clear, very good vocals.
Cons: very aggresive treble, close to being bass light. Fairly poor construction, Not very balanced sounding, Discontinued.
Another Head-Fier here helped me get a pair of these from the Koss outlet store recently. On day one I didn't like them at all. Had this very weird and unbalanced sound signature. When using them with games it's very noticeable where it's focus is. After day one I found they just had too little bass and way too much treble for me. Tried them later and had the same impression.
I have to say, these are growing on me fast. I connected them up to an E9 (!) with an HRT Music Streamer II and they sound much better.
It's close to being bass light and some sub-bass is just not there and seems to go missing. Not a big deal for me. Just not as present as on my DJ100. The mids are kind of thin sounding, but a little more forward than that of the DT-880. These sure are aggressive in the treble! More so than any other headphone I've heard. Just don't turn them up too loud and it's not so bad.
The sound from these is crystal clear. They're perhaps one of the most detailed headphones i've ever heard. If you want to be impressed, try these with classical music. For being closed, the soundstage is quite huge! Probably even larger than the K550 depending on the track.
I can see how many people would either love this headphone or hate it. With some music it's very impressive and on others, not so much. Despite it's good sound, I wouldn't call it balanced. I think it's sound clarity is up there with the SR-325is. No joke.
Comfort isn't bad and the pads are massive! The build quality is pretty poor for something that once cost $250. I imagine most of that went into the sound, but it did have a lifetime warranty. I bet if this died, they'd still honor the warranty and give me something else!
I bet these would sound best with a warm amp/dac. I'm using a Canare interconnect cable and that seems to help to tame the treble a tad and improve the mids a little.
I only have maybe 10 hours on these so far, so I'll edit this review if anything changes.
Closest match to this signature i've heard is maybe the DT-880 or maybe the Grado R-325is, but with less mid-bass.