The IE600s by contrast seemed far better balanced, indeed their standout quality was that nothing stood out as wrong. The A8000s I immediately recognised as bright and lively, with a character reminiscent of the Dunu Lunas.

It is a likable presentation without any faults and most users will probably find it to their liking except the ones who prefer purposely mannered tunings. I tested all with apple dongle dac. My CTH gave hissing sound to ie600 and 846, not sure if its the amp or iem's sensitivity. But there are also downsides. For styles like thrash and death metal that feature high-speed, distorted rhythm guitar, the IE600 seems to spotlight the buzzing top end of the distortion instead of the thrust of the chords. Or in a song like Sylvan Esso's "Moving," with a lot of sizzling synth tones, the IE600 seems to emphasize the hissiest frequences. The IE600 isn't going to smooth out any extremes of a recording. And if you're sensitive to sibilance, the IE600 are likely to trigger you unless you dial in a different EQ. (I didn't play around with EQ, though I would if I owned the IE600, taming the treble and maybe rolling off a tiny bit of bass.)

Sennheiser's IE 600 earbuds are wired in-ear studio monitors with a luxury feel that will charm and delight

Right out of the gates, I would summarize the Sennheiser tastefully done V-Shape. Just by looking at its graph, it’s pretty obvious what was the objective traced for the monitors: A prominent bass and upper treble elevation, with just enough pinna gain for the mids to not feel that much recessed. Depending on each's own personal neutrality, some folks might even consider this more of a U-Shape than a V-Shaped IEM. As we get into the higher ranges, there is a bit of a peak that can suddenly appear now and again, giving the sensation of a bit of brightness that can come across a little harsh, such as brief appearances in “ Sugar” by Francesco Yates. Sibilance is mostly controlled, although not eliminated, making “ Code Cool” be just hovering on that sibilance mark, without actually getting there. I really do suggest listening to the IE 600 in balanced mode, as it really performs better. You get the best technicalities, with more note extension, airier mid and treble presentation and a wider soundstage.

The cables comes in 3.5 and 4.4. They look very basic but the more I used the IE600 the more i liked them. I never had any tangles and there were never any kinks in the wire. It’s also really nice to have the 4.4 cable. In Paul Simon's "Can't Run But," the fitful percussion and J. J. Cale's guitar curlicues glimmer throughout. The percussion that's spread across "On the Corner" by Miles Davis -- trap drums, tabla, cowbell, congas -- is differentiated and distinct. And every scurrying piccolo and clarinet in Valery Gergiev conducting Stravinsky's "Rite of Spring" streaks brightly through the pagan wilderness. The IE 600 might have been expected in the sense it was logical that it was going to arrive at some point and it would almost certainly be built around a single dynamic driver but what has arrived is, in some ways, the most surprising of the three models. It’s why this is going to be a full length review rather than the half length one I’d originally planned for it. Not only are there some engineering solutions present here I’ve never seen before, the design philosophy of the IE 600 is singular too (I’m not going to use the word ‘unique’ because it isn’t but it’s certainly rare). The micro details are good and have some sense of clarity, but not everything is all sun and butterflies, as the tuning is rolled off in both spectrums, and it’s slightly noticeable - despite not affecting my library as much. Another point against and that needs to be noted is that the upper regions timbre can get slightly off, especially with ultra bright sources, giving a sense of metallic taste. In my experience, it really shines with more analog sources like the Cayin RU-6 R2R dongle. Despite being the only one with recessed mids, this is just slight, and the upper mids/lower treble is very well done, on par with the Zen Pro, but coming out with the worst vocal presentation of the shootout. Stage size is the weakest point, as seen above in this review, but the imaging is good and it’s the most resolving IEM in this single dynamic comparison, giving a high sense of macro details and clarity, having the best extension on both poles.

Among the very best earbuds

Now, I do understand this. I own not one but two watches which are, when all is said and done, less accurate than simply glancing at my phone so I can certainly understand the bespoke appeal of the IE 900 but I also have to say that mentioning as an aside to someone “yeah, they’re made of Amorphous Zirconium” has a certain charm to it as well. Sennheiser feels that the target for these is predominantly male, aged 20 to 40 and may well own a selection of earphones and DACs for different tasks. I think this is a fair assessment of many people active in this sort of sector but I think it underplays the group of people who are drawn to something new and technically interesting and I suspect that the IE 600 might steal more than a sale or two off its big brother for this reason. The bass is tight, fast and well controlled with natural recovery and great layering while it is clear and resolving. Cymbal strikes and electric guitars still sound great and natural, despite the dip. Lust For Life by Iggy Pop or the Larnel Lewis’s drum solo on Change Your Mind prove just that, along with Jason Richardson -Titan that also shows this contrast on more busy passages.

vs zen pro : ie600 sounds more energetic and resolving yet, zen pro sounds more neutral and calm, but could be bit boring for me

What should you get instead of the Sennheiser IE 600?

The IE 600 is tonally neutral, intimate and has an emotional sound. This ensures a true-to-life voicing that is especially expressive for vocal performances. This voicing lends a presence and intimacy that brings listeners closer to the music, allowing them to discover new accents and details. Next to that you get a steep bass slope resulting in a powerful yet fast and accurate low-end response. I got to hear these as part of the IE600 tour, and they're now on the way to the next listener. Thanks @ericpalonen for the loan. Opinions here are subjective, unvarnished and unquantified.