In response to all the posts commenting about the sonic quality differences between the beige 598 and the black special edition, I just received my SE (special edition) today, and I'm pretty sure I hear a difference. First some history. I bought my first 598 (beige) about a month ago from Amazon. I loved them upon first listen. I was especially pleasantly surprised with the decent amount of bass after reading so many reviews here and on Amazon that say they are bass light. My only major complaint was the cable length and the silly 6.3 mm to 3.5 mm adapter (instead of 3.5 to 6.3), which makes a connection to my iPhone 6 look ridiculous due to the size. I was planning on buying a shorter cable, but then I saw the black friday special on Amazon for the SE for $95 with shorter cable and jumped all over it. Even though I prefer the beige look, the SE was $45 cheaper and with 2 cables. I had to return the beige before the SE arrived, so I couldn't do side by side comparisons of sound, but here's what I hear:
First thing I noticed is less bass on the SE. The beige, that I put maybe 50-100 hours on before returning, was fuller and more prominent in the bass with more impact that resonated. The next thing I noticed is that vocals on some songs were slightly hissy and ever so slightly sibilant on the SE. I never heard even slight hissiness or sibilance on the beige 598. As I'm listening to the SE now, they sound brighter and thinner than the beige ones I returned. I remember the beige ones sounding warmer and fuller with slightly more relaxed upper mids and treble. The overall sound signature is similar with similar soundstage, however. The biggest noticeable difference is the lack of warmth and fullness in the bass and lower mids.
Regarding the comments about authenticity, I checked mine on Sennheiser's site and they checked out as authentic.
So, do you guys think that the difference I'm hearing is due to break in of the phones? Can I expect these SE's to get fuller and warmer sounding over several hours of use? The only issue I have with the break in possibility is that the beige never sounded like this even from day 1 from what I remember. Also, I'm using the short cable with the SE. Could the difference in sound be due to the different cables? I'm going to try the long cable with adapter and see if I hear a difference. Also, is it possible that the exact same model headphones can differ in sound due to slight manufacturing variances?