[aras]

I guess I'm late but I would recommended W4 over UM3X any day. UM3X bass response is way too much bloated in my opinion. Also mids are supersmooth blurry/dreamy which takes away from transparency compared to W4s especially when listening to vocals. Finally UM3X soundstage is significantly smaller than W4. Overall W4 is the "refined, well balanced" IEM

 

[xaddictionx]

Pulled the trigger on the UM3X, looking for an alternative to my Shure SE535's. Regretted that decision very quickly. Almost immediately obvious that the SE535 are very similar and slightly better, IMO. Here are my first impressions after trying my best to like these, A/B comparison (back and forth) with my SE535. Sources are Sansa Clip+ and H140/d10 optical out, music was rock, prog rock, metal.

Ergonomics: I agree this is great. The lighter cable is nice. No microphonics. The earphones themselves fit very nice inside my ears where the SE535 stick out a bit. No complaints here. The Shure olives work well on them. Sound can cut out if you try to wear a headband over them though, same as my Shures. Not sure why that happens. Doesn't happen with the triple flanges, but they are very uncomfortable of course.
Bass: Very good to excellent. Similar. Possibly more detail & impact. Maybe these are being tuned for drummers and not just "musicians."
Mids: Similar if not the same.
Highs: My biggest complaint. The SE535 has significantly better highs (which is hard for me to believe). When I first got the SE535, I thought they sounded like mud. I couldn't even tell there were highs (but to be fair, that was coming from the bright ER-4S/P). Well, the UM3X sound like mud x2. If you want to called this "recessed highs" or a "veil" then that's another way to say it. The opposite of what was I was hoping for. Now I can tell my SE535's have highs, and they're not as bad as I thought, maybe OK even. There is nothing even close to sparkle in these earphones. I think if I would have read the posts a little better I would have seen that no one has claimed the highs are good, it's all about bass and mids and detail. I should have looked for that more specifically.
Instrument separation: Not hearing any improvement vs. the SE535. Except for maybe more detail in the bass drums/guitar. Not getting why this is supposed to be a strength of the UM3X. Compared to what?
Soundstage: Yeah, it's close as described by many. Closer than the SE535. I don't like it. But I was expecting this so not a surprise.

Overall, very smooth, as described, but also very similar to the SE535 with emphasis on the mids and lows, but lacking even more highs. SE535 are brighter (but certainly not close to "bright."). Guitars sound much better. So why would I want to keep these and my SE535 at the same time? Will probably send them back. Bummer.

I would say that the highs of UM3X is not muddy. It's more to "lazy" treble. The UM3X sounds pretty flat and lazy with a bass boost. The mids are also forward but with lush. Being a previous user of UM3X, I was put off by it's lazy treble and highs as well as the constricted soundstage. Though I would compliment it's amazing instrument separation. Even after a month of usage I couldn't accept the presentation of UM3X. Even paired with a silver dragon cable, the constricted soundstage does not seems to have widen. Silver dragon cable improved the clarity, treble and highs. But not to a very vast extent.

I would recommend the W4. It has a much wider soundstage whilst retaining the good instrument separation. Treble is extremely smooth, mids are lush and not forward. Highs are well extended and smooth. Just a note, I find that the W4 have a slight "veil" at the lower mids region which can be irritating at times especially prominemt on lower bitrate tracks. However, pairing it with silver dragon cable, the "veil" seems to have disappeared and I'm enjoying them every moment!

 

[tracyrick]

Some good comments here. I'm committed now to trying these for 1 full week. I wasn't looking for "balanced" or "neutral" which is why I avoided the W4. Upon further listening, I still think the UM3X has weak treble energy (or whatever you want to call it) and overall is very similar to the SE535. So it doesn't make much sense to own both. I am 110% sure the SE535 has more sparkle in the highs and is a slightly brighter earphone. I was hoping for the exact opposite, I was hoping that the UM3X would be better at highs than the SE535. Shame on me for not catching that by reading the posts since there aren't many impressions like that.
 
Positives with the UM3X:  The overall "muddy" sound impression I was getting is not as bad, now that I'm getting used to it. The clarity and natural sound of instruments in the low end continues to be strong. At this point I'm guessing I might like the treble better in the W4, but if the sound is relatively flat otherwise I'm not going to want to keep it. The W3 V shaped tuning sounds appealing - and more different from the SE535 than the UM3X is - but there are many comments about why the W3 sound doesn't quite work.
 
Throwing out a curveball here, one headphone I have that I really like is the Grado SR 80. Like my anemic Ety's on steroids. The bass is good and impactful and the trebles are great, with no bloated mids to cloud the sound. Almost too weak on the mids though. Sounds like none of these Westone earphones sound like that, although maybe the W3 is the closest. The Grado is of course also much different from the SE535 too, but I can't ride a bike with helmet with my Grado's on.

 

[aras]

You may wanna try Grado GR10 in that case. 

 

[Fungus]

I now have both the um3x and W3's. 
Does the W4's have an even larger sound stage than the W3's?

 

[Spyro]

I don't think so.  I would say quite similar.  Very nice distance.

 

[Fungus]

I actually find the um3x to have much better treble retrieval and bass quantity than the w3's. 
If not the for the expansive sound stage and the ergonomic cable, the w3's would probably not be here. 
The fit of the w3 is also not as good as the um3x mainly because of the short nozzel and the tendency of the earpiece to gradually angle downwards in a clockwise direction.