The OP has been updated with a brief blurb about my visit to DUNU headquarters earlier today. I've also got a pair to listen to at home now, so I'll be doing a review on them.
Honestly, I've been tough on DUNU in the past, but I believe everyone can agree they've come around with their hybrid models, and this new endeavor into titanium coatings is moving the company's products even further in the right direction. The DN-2000J, in my opinion, possesses the highest resolution of any DUNU earphone and comes very close to the level of detail of TOTL IEMs, but in achieving high resolution and treble extension, sacrifices treble linearity. The Titan 1, IMHO, is less of an issue when it comes to treble brightness, though it does have some small issues on that front.
I've managed to settle on RedGiant's red-core natural acoustic tips. Their opening diameter is wide enough not to confer any reverse horn effects, but the it doesn't have the treble resonance issues of some other tips nor the tendency to muffle the lower midrange. The result is the most open and natural sounding response I've heard from the Titan 1 so far, preserving treble extension without extra resonance.
The overall signature of the Titan 1, even with these tips, is still a mild classical V-shape. The lows and highs take precedence over the midrange, which is clear but not forward positioned within the stereo image. For this reason, I still find the midrange of the Sony MDR-EX1000 to be more transparent, despite the former Sony flagship's lower treble resonance that occludes some of the treble detail, its midrange is better formed, and thus its center image (which usually comprises vocals) projects deeply and three dimensionally. The same is true for some of the better CIEMs that I have --- their neutrally-tuned midrange responses enable their vocals and center image in general to project forward with warmth and body without sacrificing clarity.
On the other hand, the Titan 1 is good at delineating voices because of its elevated upper midrange and parts of the treble. Coupled with the fast transient characteristics of this titanium-coated diaphragm, the Titan 1 exudes excellent "edge clarity". However, because the central midrange portion is still a bit recessed in relation, imaging cues are relayed mostly side-to-side, with far less front-to-back information.
So yes, make no mistake, this is no back of a smoky jazz club, listening to a sultry-voiced siren kind of earphone. The Titan 1 is most at home when its given a lot to do, leaving the sprightly titanium-coated driver to sort out the details and separate out the instruments. Thus, the V-shaped response of the Titan 1 makes it palatable for many types of popular music where the beat, not the voice, is the focus.
Remember a young, pre-queen Bey teaming up with Kelly Roland and Michelle Williams? Destiny Child's 'Say My Name' plays to the strengths of the Titan 1 --- most of the track's metronomic rhythm is sequestered in the low bass and upper treble. Same thing with the hypertonicity of J-Pop music --- electropop/hip-hop outfits like M-Flo are flattered by the sound space the Titan 1 is able to throw out.
So what about bass? Just listen to Iggy Azalea's 'Work'. You'll go "head over heels" for the kind of simultaneous control and power realized by the Titan 1.
That's all for now (I know, it looks like I already wrote the review, but that was not it). First, a photoshoot...
Thus far, I've only had time to get a few shots off with good lighting, but will be taking more as time continues. The one above is an out-of-camera JPEG; luckily, as the earphones are brand new, the picture needs zero editing. The polishing on the metal housings aren't perfect, but I'm still able to get decent soft-to-specular highlight transitions even with a latitude-compromised JPEG file (and a 9 year-old camera).