It's all about presentation. For example, you can take three very treble savvy earphones, the CK10, the Triple.Fi 10, and the RE252. All three of these offer both excellent quality of treble as well as limitless extension on the top end. At the same time, they present the sound different from each other. The CK10 offers the most micro detail and raw information but is also slightly tame in terms dynamics and edginess. The RE252 is a little more direct in presentation and although it has less micro detail it has a little more emphasis and edge to the note. The Triple.Fi 10 carries good detail and a decently edgy note but also a sweetness.
Stepping back to the SE530, the extension is actually there. If you run a frequency response test, it actually doesn't roll off on the top end. However, it is recessed a little bit that slightly makes the highs a little behind the midrange. This apparently was one key aspect Shure fixed with the SE535, so I expect a great top end on the SE535. The SE530 was good, but it had some sort of phase or time delay issue either with placement or x-over that delayed that treble just a little bit. The UM3X is more towards the CK10 in that it offers a lot of detail. It isn't the same, more like the ER4S than anything else. I want to add the frequency response that I hear with the UM3X. This might give some insight into why it sounds the way it does.
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The dip has to do with the x-over. I don't know if it's just gapped or out of phase or specifically geared to have that response. I will note that this response may actually be close to mic flat if we compare it to the ER4S response graph. The ER4S has nearly the inverse of this response and is perceived as close to flat once we take ear effect out of the equation. Maybe Westone ignored the idea of the 2kHz natural boost lost from an in-ear setup, or maybe they had different intentions with the earphone. It may end up being tip sensitive and shallow versus deep insertion too. I know they sounded a bit different with the long Comply tips versus the short ones or swapping to the Shure foams. It's tough to say. Now this is also how my ear hears "flat," so take my response above with that in mind. I haven't owned an ER4S for a while, so I can't directly reference back to it. I know when I did toy with frequency response testing, I did perceive it as relatively flat, but that's apples to oranges without more recent use or a direct comparison.
I'd be fun to grab another ER4S again. I liked the earphone, but I still think it's a bit limited in breadth of capability sticking to a single driver. I'm curious how different the SE535 is to the SE530, not so much the big picture but in the small details. I did perceive those as relatively flat short the slightly recessed highs (now fixed) and low frequency roll off.
I've bought and sold two UM3X earphones. I've sold them for the same reason twice: lack of realism. They offer a very revealing and detailed sound, but they are blatantly artificial in presentation, and it's something I could never justify holding onto. I have come to view them more as a tool than a musical device. They're a high level tool that's competitive in performance with most everything out there, but they function more towards a tool than a musical device. If they were less artificial, they'd be awesome, but it would require a whole different package of drivers and essentially a new sounding earphone to do so.
On the contrary, the SE530 I owned was one of only a couple very realistic sounding earphones I've used. It has a very lifelike presence, although I felt the notes lacked body to create a full enough presence. I sold the SE530 too though because it was too limited with the low end roll off, recessed highs, and goofy sound stage placement (apparently improved on the SE535 too). Although I have a hard time justifying straight out buying a pair, I'd love to demo a pair sometime to see how the differences improved the end product. If the SE5535 is improved enough, it could regain competitive status in my eyes.
Too bad I know I like a thicker, more textured note though. I really like the ER4S, Custom 3, UM3X, and CK10 for this as they offer a more robust note than the commonly thought of squeaky clean BA sound.
