@WCDchee
thanks for taking the time to write detailed descriptions, they provide a good image of U18 and Fourte. But I must say I am a bit surprised by the comparisons. You mention you found Zeus technically disappointing, while Vega is the only one to come close to Fourte. Was wondering if you could elaborate to what kind of aspects you are referring to with that, is it based on purely technical aspects or preference based on signature?
I find Zeus technically superior to the average TOTL iem in resolution, stage dimensions and separation, including Vega. While I agree Vega is a wonderful sounding iem, I wouldn't necessarily say it is one of the most technical iems. Even according to Campfire's own published graphs, its treble extension reaches up to 12 KHz, which might be slightly better than average, but not as far as others.
I've had a lot of experience with IEM measurements myself unofficially, and from my interactions with industry personnel and engineers, in the confines of IEM measurements, frequencies above 12-13khz are not reliably charted on the frequency curves. This is due to the increasing amounts of resonant peaks and the types of compensation that would have to be applied and the likes, and as such, we cannot just simply take it at face value.
In fact, even the Shure KSE1500, which has a published FR of up to 50kHz (and I have no doubt has crazy extension up to 20k from my listening tests, and by virtue of the fact that it is an electrostatic driver), shows marked dipping past the 10khz point.
Also, I feel that measurements should never be taken in isolation. Comparisons are only valid when the same setup and calibration curves are used, hence my respect for big databases over individual measurements.
Don't get me wrong I'm not in any way criticising your ability to interpret measurements, just stating things as I understand it.
With regards to the technicalities of the Vega, I can see why it's not considered by some to be the most technical earphone. It is coloured, no doubt. Very thick, somewhat dark, and with a very gentle and even soft top end. It's tuning is by no means neutral.
However, I maintain that it is one of the most technically proficient earphones to my ears because of a few things
1) Resolution - it may not be bright and sparkly up top, and as such details might not jump out at you. But if you listen closely, the Vega resolves
fine textures and
space between instruments remarkably well. It is extremely rare to find something with such a thick and warm tonality that resolves such details so well. A good example I feel is between the Arthur and the Zeus R. They are essentially the same in design but the Arthur is just warmer because of the change in wiring and cables. And in comparison to the Zeus, the Arthur starts to sound more smeared. Now the Zeus isnt actually more detailed, it just seems so. The Arthur just presents detail less obviously. With the Vega, however, despite the thickness, fine textures show up remarkably well. For me this is the mark of resolution. Not whether or not I hear that little drum beat here and there, because somehow unlike others I never seem to miss out instruments even with cheaper and poorer earphones, but rather, whether I can make out the raw textural differences in the voice or the instrument, whether I can make out the way the air and space is resolved between different sounds, How transparent and black the space isfor me to hear through the mix. That is what resolution is to me. And that, the Vega does better than pretty much most of the TOTL competition out there to my ears.
2) Dynamics - The vega easily takes this when compared to multi BA designs. Then again, this is never a strong suit of BAs. Sure they might be quick and precise, but they dont hit hard. You don't get the same Visceral bass response from a BA setup as you do on a solidly implemented dynamic setup. And this presents not just in the bass, but across the spectrum, everything just hits harder when it has to. With the Zeus or the Arthur, I never get the physical sensation of the sound actually hitting me. I just hear it. With the Vega, It feels like waves of some come crashing against me when called for.
3) Imaging and staging - Now, the Vega might not be as spacious as the most spacious sounding IEMs like the Andromeda, but it is pretty close. In terms of imaging, BAs tend to be a little sharper and more precise, with Dynamics tending to smear that just a tad. However, When comparing the Vega to the Zeus or the Arthur for example, the solidity and the weight of the image really pulls ahead. In BA setups, while the location of the voice for example might be very precise, it doesn't feel real, it doesn't have that physicality. With the Vega however, it's solid, its physical and real.
I hope this answers your questions.