These sound like pretty good iems but I just want to point out the marketing just sounds like fluff for carbon nanotube diaphragm. I have a bit of beef with marketing fluff so don't mind this rant, just trying to say I wouldn't put too much salt into the any marketing hype, its mostly just all buzzwords. On another note, here's an interesting research paper on the effects of cnt on dlc film, measuring young's modulus:
https://www.researchgate.net/figure...CNTs-doped-diamond-like-carbon_fig1_259418097
Claims of things like lower distortion are pretty silly cause even cheap $50 DD iems can measure very low distortion, and in fact lower than much more expensive iems. Really stiff drivers are very good for low distortion in high frequencies, but less stiff ones have lower distortion in low frequencies. Main way around this is to use composite drivers with stiff domes, and not stiff surrounds. For example, I believe the moon drop illumination does this using a peek surround and lcp dome. There's an excellent discussion on this here:
https://www.reddit.com/r/headphones/comments/bacd37/-/ekaxsri
While composite drivers are expensive on large full size headphones you can find them even in cheap iems these days.
Different diaphragm materials will be better for different things, but beryllium is usually considered the best because of all the highest young's modulus materials it's the lightest by a long shot.
Really though, my main point here is, most of the marketing fluff between different companies is really just advertising the same things but in different words and are sometimes just straight up inaccurate or untrue (like the zex "electrostat"). Bio diaphragm driver? Probably just titanium. Graphene/dlc/cnt driver? They're some form of carbon driver, some will be good some will be bad but how they're being named or marketed is not an indicator of this at all.. the young's modulus alone between a good and bad one is SO big. We don't even know how many layers the diaphragm materials is (less is better). Beryllium or titanium driver? Could possibly just be titanium plated or beryllium coated. Composite driver? Well, we have no idea what surround material or dome material is being used, but a lot of manufactures don't even list/advertise what surround material is being used.
The main reason this marketing fluff is all moot, is that because even if there was a grain of truth to it, the dynamic driver will still only be as good as it's weakest link, and there are soo many factors to consider like the magnetic force (Tesla flux), diaphragm size, diaphragm stroke depth, resonance of the cavity material, cavity shape, damping factor, tuning, design and implemention, etc. I think we're all better off ignoring the marketing fluff because it would take an experienced and knowledgeable audio engineer PLUS all the data that most manufactures don't make publicly available to us to make heads or tails of all the marketing hype and if there's any weight to it. I feel it's one of those things where the more you know, the more you realize how insubstantial what you do know is and how out of your depth you are for even trying to understand.
This is off topic and not in response to your hifiman iem impression but I just want to say if anything I've realized even cheap iems can be good, and that you don't need the most expensive materials to make good stuff, and more over that you don't need the most expensive iem to get a good quality one. It's all about the design choices, implemention and quality. Of course good quality stuff will cost more but some companies/brands just straight up mark up things by ridiculous lengths just to sell their stuff as more premium. Just looking at some all ba sets and comparing how much the material cost would be to buy the main components for diy you'll quickly see brands like kinera and hifi boy charge ridiculous amounts compared to other brands selling similar level stuff for much cheaper. I haven't looked into too many brands yet but of the couple I've looked at, brands like bgvp, thieadio, and gs audio are usually very good about not marking up their iems too much more than their actual component costs, at least for the iems I checked which had their ba models listed. Brands like fiio, fearless audio, etc were somewhere in the middle about it. The particularly bad ones I noticed were brands like kinera, hifi boy, campfire and penon. You're basically paying a LOT for their inhouse sound, tuning, and designing chops, but are any of their iems really worth that difference? I think it's probably subjective but doesn't change the objective fact that you can get similar level iems for much cheaper than what I will call the snake oil brands. Some of these brands (cough, campfire) selling kilobuck range iems even use cheap bellsing clones.. do you know how cheap those are? You can get a compound/dual twfk driver for less than $5 for diy, whereas genuine Knowles stuff will cost four times as much or more for diy. Do your research guys, try to make informed purchasing decisions after a little due diligence. Don't buy into marketing fluff. Don't get fooled into thinking stuff is better than they actually are, relative to cheaper stuff I mean. You'll be surprised what you might learn and will save yourself from overspending on stuff that isn't worth it. Trust me, the iem market is saturated enough to have stuff that's as good quality as the snake oil brand stuff but for much less, just gotta search for it and do your research. If you're lucky you'll be able to find something that's just as good as the more expensive stuff without the expensive markup, and a tuning you actually like. The struggle is trying to find iems that fulfill both criteria, so good luck to everyone trying.
...now that they're grown up and I'm easing into semi retirement, its nice to be back here and chat with old friends about this hobby.
