This is a Review of Audio-Technica CKR9 and CKR10 premium dual-driver IEMs, http://www.audio-technica.com/cms/headphones/1108c4542caf5790/index.html and http://www.audio-technica.com/cms/headphones/df517c93c488bb58/index.html From Audio-Technicas SonicPro "a legacy of sound" family, I have a pleasure of introducing to you their ATH-CKR9 and ATH-CKR10 premium in-ear monitors. Though not exactly a brand new release, these are finally available from Audio-Technica US which is a great news since now you can rest assure your purchase will be covered under a local (outside of Japan) warranty. This has been a topic of a number of discussions I've been involved in after my review of ATH-IM02 and ATH-IM03 IEMs. When you invest money in a premium quality headphones, especially something like CKR series with non-removable cables, it's nice to have a piece of mind with a local warranty from an authorized dealer. So what is so special about these CKR9/CKR10 models? Introduced earlier this year, Audio-Technica presented them as a first IEM with a dual phase push-pull drivers configuration. It's quite an interesting concept where instead of a traditional config with both drivers facing the same direction toward the nozzle of headphones, these 13mm drivers are facing each other while being wired out of phase. There is some science behind this design which in the past was only implemented in full size speakers to reduce harmonic distortion and unwanted vibration. Here, it was scaled down to IEM size with quite an impressive results delivering high resolution sound. Though they both feature a similar design, these IEMs have a different tuning and a different housing material where CKR9 uses aluminum while CKR10 has metal-coated titanium, both inside of a plastic outer shell. Also, with a rated frequency response of 5Hz to 35kHz for CKR9 and 5Hz to 40kHz for CKR10, the later one qualifies for "Hi-Res Audio" certification. I know spec numbers are important for some people, but at the end what counts is the actual sound you hear with your own ears. For this review, I will start with a common section dedicated to unboxing and the design details, and will go into individual sound description followed by comparison with other IEMs. So without a further due, here is what I found. Starting with a packaging, both CKR9 and CKR10 outer sleeve greets your with a high res picture of these little beauties with a distinguished detail of Aluminum silver-color theme of CKR9 and Titanium gold-color theme of CKR10. On the back you have a lot info in both Japanese and English with a list of features, specs, and the close up of the internal drivers config. One thing is to read the description, but it's a whole different experience to see the actual detailed assembly of the drivers. It also shows how much pride AT takes in their product showcasing their design, similar to what I found with their IM0x IEMs. After sliding out the sleeve and removing the top cover, both CKR9 and CRK10 models have the same display presentation and identical accessories with IEMs inside of the foam cutout, a premium leather case in the lower left corner, and a set of eartips in the lower right corner. CKR9 unboxing and accessories: CKR10 unboxing and accessories: Looking closely at the design of CKR9/10 series, you will find them almost identical with an exception of metal part of the housing. Starting with a plug, you have a very sturdy 90deg hard plastic housing and gold-plated connector with an excellent strain relief and enough extension to fit any audio player or heavy duty phone case. The only difference here is a slim metal ring detail on the plug of CKR10 to distinguish its premium appeal. Moving to the cable you have a soft rubber shielding which is a bit sticky and unfortunately prone to some tangling. The cable design is partitioned in a way where you have a left/right wires from each earpiece with signal/ground going all the way down to 3.5mm connector keeping the ground wires of L/R sides separate. As a result, you have a very basic y-splitter clip separating individual wires from a dual attached one going to the plug. There is no chin slider which is not a show stopper since it's usually helpful for over-ear fitment, although it makes me wonder if chin slider would have been helpful to keep cables from moving to mitigate a considerable amount of microphonics introduced by the cable. Moving up to earpieces, first thing you will notice is a high quality strain relief. Considering CKR9/10 don't have a removable cable, I was very pleased to see a well designed and attached soft rubber tube strain relief that was sturdy enough to be handled even while removing headphones from your ears. I found the shape of the shell to have a perfect size (not too big or too small) and an excellent fitment for my medium size ears, and we are talking about two rather large drivers enclosed in a metal housing surrounded by a plastic shell. To improve ergonomics of fitment, CKR models have a cable attached at the front rather than back allowing a more comfortable inner ear fitment. Together with an angled nozzle I found it to fit my ears like a glove, even before I started tip rolling. I guess there is a way you can try over-ear wiring, but the extension of strain relief will get in the way. Another thing worth mentioning, there is a slim port opening on the back which I assume actually functioning rather than for looks.