So I'vee been A/Bing the CKN70 (with about 50 hours burn-in) to the RE-400 (with about four hours burn-in):
CKN70: A noticeably wider soundstage than the RE-400 (not significantly wider, but it's noticeable). Notes are a bit more thicker than the RE-400 (but not by much). Definitely more bass and treble is on the verge of being too harsh. This is marvelously refined sounding earphone (although the cable still bugs the hell out of me).
RE-400: A bit smaller soundstage, but the RE-400 clearly wins hands down in refinement, clarity, and details details details!! Someone described these as microscopic earphones. That person didn't lie. The RE-400 seems to slice right down to the heart of the notes. Female vocals (and male) are some of the most natural sounding I've heard. Notes are just a little bit shy of the 3-Dism of the CK70, but not by much. Yes, the CKN70 has the wider soundstage, but the RE-400 win in depth back and forth. I mean the notes are so rich, but detailed and clear, unlike the CKM500. There is better instrument separation in the re-400. And with all the clarity , the bass is still there and goes deep enought to hear every note. While these aren't bass monsters, the earphones is nowhere near bass deficient. Plenty of audible bass in this balanced and neutral earphone. I didn't want to like the Re-400, but it's irresistible! The timbre and imaging are mindblowing. This earphone belongs here in great finds, but you will be hard pressed to find a better sounding earphone at original $100 MSRP. I know some of you may be reluctant to try it because of fear of lack of bass, but it's there (about as much as the GR-7, but of better quality)
waynes world this is like a mixture of the HD70 with more weight and bass, better instrument separations, and way more detail. I hope more of you give this (and the H-200) a chance.
Both earphones are worthy, but even with the CKN70 being cheaper by $30, the Re-400 is clearly technically better.