After reading the original post about the598se, completely lacking in bass; I was thinking along the lines of, it was a matter of how much bass one likes, or is used to.Go with what @KopaneDePooj said. Do YOU hear a difference? I can tell you my one story with the 2 cables that came with the 598 SE I ordered a few years back. First, I used the shorter, thinner cable and it's all I used for at least 2 weeks. I hated the sound. Not because of the cable. There was something "wrong" with the sound of this particular 598 pair. Bass was very weak and treble was too bright. After a couple of weeks, I tried the longer, thicker cable - the same cable that comes with the ivory 598s. I "thought" I heard a slight difference between the 2 cables. Comparing back to back and with the new ivory 598 I'd just ordered, I found the longer, thicker cable to sound slightly warmer and more 3-dimensional (wider, deeper soundstage). It's possible it was just in my head, but I think I heard a slight difference. In contrast, the differences between the ivory and SE pairs I heard with the same cable, were obvious. 100% certain the cans themselves sounded different.
But, after reading your posts, since you have owned both, and hearing the lack of bass compared to the Ivories,
And mathieulh, hearing a lack of bass compared to the6xx and 58x, I was starting to think, the 598se were different than the Ivories
However, mbwilson111's comment that the 598se - would not be for bassheads, but they have nice bass - , is how I could describe my Ivories.
So I guess, there are at least some 598se that are "off" for some reason.