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.
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.
Agreed. I highly doubt that the "bad" pair of 598 SE I received were the only pair like that in existence. To be fair, when I brought this up at the time, there were members who posted that they had the opposite experience, with the ivory 598 sounding noticeably weaker in the bass than the SE. Which leads me to believe that it's probably the same driver assemblies being used in both the ivory and SE models, and some driver assemblies were manufactured "out of spec." It's strange though because before the black SE came out, I don't recall anyone bringing up this significantly noticeable difference in sound signature between 2 pairs of new ivory 598s. Maybe someone did and I missed it. I sure haven't read every single post of this thread or other 598 threads, so there's that.
BTW, I agree with mbwilson's description as well. Not for bassheads, but definitely a nice bass to them. I would go further and say that they have perfectly adequate bass for most songs and are only lacking bass slightly on some songs, especially ones with low bass.
When I got my first pair of 598s, I was a bit concerned due to some owner reviews saying they were light in the bass. Knowing this was subjective, I took a chance, and it's the best decision I've made when it comes to headphones. Upon first listen, I was pleasantly surprised to realize that while they were slightly light in the bass, they were more than adequate. I had no regrets and still don't. And I was coming from a Porta Pro being my main headphone, which has quite a bit more bass. The 598s do so much so well, that even though they are slightly light in bass, it's forgivable, and it's never to a point where the bass is seriously lacking. Of course, if you primarily listen to bass-heavy, especially low bass-heavy, genres like rap, hip-hop, and EDM, and want to really feel the bass and rumble, then I'd suggest a suitable closed/sealed can instead. While I consider the 598s perfectly adequate for most songs of these genres, especially with bass boost enabled (more below), there are better cans out there if you want to really feel the bass from these genres. For such folks, I surely wouldn't recommend an open back can, except maybe some planars.
One last tip. For anyone that owns an HD 598, and feels the bass is lacking, something like a Fiio E10k with analog bass boost switch, helps quite a bit. In the E10k's case, it will muddy up the low mids a bit and add heft to male vocals, but it may be worthwhile tradeoff for the bass it adds. If not, use the digital EQ on your player, or free software like Equalizer APO, which lets you fine tune the bass without affecting the mids.