I just did a quick demo of a few high-mid to top tier universal iems today, and would like to share my findings/conclusions.
I tested the Westone 2, Sennheiser IE8, AT CK10 and AT CK100 together with my trusty Westone UM3X. I have also owned the Phonak PFEs (1st gen, the easy-to-break ones) and Westone 3 previously. All IEMs are tested with the iBasso B4 amp (modded to be warmer), and with 3-4 tracks.Westone UM3X
Well this is my benchmark 'cos this is the one I've been listening to daily. Excellent separation, very rich/warm mids, nice tight and impactful lows. My main complaint is that the treble is lacking somewhat, and the soundstage is quite congested.Westone 2
My first impressions (abt 2 mths back) weren't good at all. Found the sound too thin and bass lacking. But that was without an amp!
With an amp now, it actually sounds very nice, I must say. Mids are slightly below the UM3X, still very rich, and the treble exceeds that of UM3X. Definitely sounds more crisp. Soundstage was also better. Separation is slightly below UM3X, and the most stark difference is the bass. Doesn't hit hard enough, but generally acceptable. Definitely a pair of phones I will consider "downgrading" to AT CK10
The mids are quite airy, but I feel they are a little thin. Highs are way too siblant for my liking. When I listen to "I'm Yours" (Jason Mraz) there is a lot of siblance; and this is even worse with a Chinese track "tong hua (fairytale)" (Guang Liang). I think even the Westone 3 had less piercing siblance, and the Westone 3 was generally better than the CK10 is most aspects. Wasn't impressed.
This is certainly a very nice pair of phones. The mids and high had a very lush feel, and the treble was certainly very crisp. A little more siblant than Westone 2. Mids were very comparable to the UM3X.. in fact I think in the longer run I may prefer the AT CK100's. Soundstage was better too. But the bass was quite lacking. Very little impact, though speed was there. I cannot decide if I like this or the Westone 2.IE8
This is a very interesting pair of phones. It sounds no where near all the other ones tested, or even the Westone 3 that I used to own. The mids and highs sounded very soothing and warm. I think the separation isn't as good as UM3X and most of the other phones above, and the bass is too overpowering. But the soundstage was fantastic. Best I've ever heard in a pair of IEMs. But needs to get used to the sound, which I'm not.Summary
Treble: CK100>Westone2>=IE8>UM3X>CK10 (largely cos CK10 is too siblant)
Lows: UM3X>IE8 (more quantity but wayyyy too much) >Westone 2>CK100>=CK10
Separation: UM3X>CK100>Westone 2>CK10>=IE8
All in all, I think my UM3X is here to stay. I would consider the AT CK100 if it were cheaper (but its about US$350 where I am), and would seriously consider getting a pair of Westone 2 if I want to downgrade.