I was at Stereo yesterday trying out the CKR9 and CKR10, as I was interested in their dual DD in reverse configuration and the many rave reviews praising them for their naturalness (which i interpret as sounding realistic). Granted that I have been listening to the Dita Answer exclusively recently, how can I not try them out?
TL: DR, if you're looking for earphones under $250 and $350 respectively and love a realistic sound, GO TRY THESE TWO EARPHONES NOW!
An aside, I saw the new JVC FXT208 and also tried it out since it was priced very close to the CKR9 and was an update to the FXT90, an earphones that I still have. In term of naturalness, it didn't come close to the CKR9. In fact, i thought the FXT208 was not fully burnt in, since the overall sound signature was just so veiled and muffled compared to the CKR9.
Comparing the CKR9 and 10 though, they sound very similar to each other and if i was not doing a direct A-B comparison, I might not even be able to tell them apart.
Bass: They have one of the best bass I've heard in a while, a cross between BA and DD bass; most of the time, DD bass is more natural, but tend to leak into the mids due to its slow decay and "rumbleness" while BA bass is punchy, but can also be described as thin and lacking in impact. The CKR's bass in between, punchy yet not artificial and thin sounding like BA bass. If you're looking for subwoofer bass, then the CKR is not for you, but if you like BA bass but crave more impact and realism, then I will recommend trying the CKR out. I found the two earphones' bass to be very similar and any difference i heard might be due to confirmation bias.
Mids: This is where I find that the CKR10 definitively beat the CKR9. While not a night and day difference, the CKR9 is more warm in this department and I feel that the CKR10 is more neutral and natural.
Treble: Similar to the mids, the CKR10 is slightly more natural and neutral but the difference is smaller and both are very enjoyable.
Soundstage: This is the 2nd area where the difference is most pronounced with the CKR10 having the more natural and spacious soundstage. The CKR9 produces the vocal in a weird way, with the singer sounding too forward. The vocals by the CKR10 is more laid back and I feel that it blends with the other parts of the music more harmoniously.
Which to buy: normally, when two earphones sound very similar, i find that the cheaper one would provide the better value. At stereo, the CKR9 is $90 cheaper than the CKR10. In this case though, i will say that they both provide identical value and you should try them out to see which will be suitable to you based on the genre of music and gear you have.
PS: Looking at Amazon Japan, the CKR10 is priced at only $240, against CKR9's $200

Of course, this is not factoring in shipping but my point is that with only a $40 difference, I will definitely get the CKR10. Fortunately, the Dita Answer is still better in the natural department compared to both of them, so I'm not too tempted