I hadn't even realised that the HD 600s' colour scheme has changed as well until reading your post, but indeed, they look different now. While I personally really like my HD 600s' blue granite appearance, the new colour scheme looks visually more professional as well as refreshing to me, and most likely also more pleasant to most people.
Personally, I would definitely not refer to the HD 600 as "v-shaped" but rather "natural neutral"/"warm-neutral", but nonetheless find the HD 800 to be more on the v-shaped side of things, albeit with a more treble-oriented tilt in combination with a reduced but still natural sounding upper midrange/presence range (my personal perception of flat neutral when it comes to headphones and in-ears is fairly close to the diffuse-field target (I don't find a moderate boost of the lowest registers for the compensation of the lack for mechanical vibrations in headphones/IEMs compared to speakers necessary, but others may and do feel otherwise), hence most headphones that are considered as "bass-light" by many don't sound lean in the lows to me at all but sometimes even moderately boosted (while I clearly prefer models that are closer to the diffuse-field target for "serious" CD rig headphone/IEM listening, this doesn't mean that I don't own and use heavily bass- and/or treble-boosted headphones and in-ears for recreational music listening and/or other purposes such as occasionally watching film - in fact, it's actually even rather rare that I use neutrally tuned in-ears and headphones for this purpose)).
Perfectly justified and well explained reasoning! The diffuse field target does indeed have a bit less bass than the bit of room-reinforcement in studio monitor setups (and even less than many home hifi setups, but of course as a whole those have widely diverse signatures!).
I think it’s interesting to go back to 90’s and earlier music. Synthetic bass-drenched music seemed (IMO) less common back then, and the midbass and sub bass of the HD 800S is plenty for Nirvana, Paul Simon, Pink Floyd, Steely Dan, etc... The rare exception like the famous and taste-setting “Angel” by Massive Attack still lets you hear the deep opening notes and has air-pushing impact, but I think part of what we expect in more modern music is to hear a track like that with the bass blooming, dripping down and over the whole track like a thunder cloud to convey a sense of threat and power overwhelming.
I think the IE 900 has a bit more bass than the HD 800S, but it is also very tight and low distortion. I like it stock, but it also provides a clean baseline (bassline?) where people have the option to add distortion and crosstalk with software if they are in the mood for a more overwhelming emotion. Personally, so far I haven’t wanted to change it yet at all, and found it very emotional.
Does it sound like the ie800 given they have a similar driver? Does the shape of it make any difference? I wanted an expensive ($2000) new sound design IE80 I guess.... that would be the ultimate. Not a rehashed ie800. Should I buy a Dita Dream instead?
Oh, you should check out Jermo K’s post in the Q&A thread for details! Other than sharing the 7mm diameter, everything about the driver membrane polymer, permanent magnet, em coils, back volume, diffusion with the acoustic vortex, tuning with the Helmholtz resonators, external shell and detachable cables, is all new from the ground up.
EDIT: there’s a couple posts of info, here’s one of them:
https://www.head-fi.org/threads/live-q-a-ie-900-with-jermo-koehnke.957764/post-16353757
Also, not to disparage anyone who loves the sound, but the IE 900 absolutely slays my IE 80S on a technical level. The IE 300 would be the most direct upgrade to the IE 80 and IE 80S, with similar bass quantity around the IE 80 at its lowest setting (which was still strong), but the quality and distortion is on another level.