After having enjoyed the Zeus for quite a while, I think I can reasonably give some feedback on my feeling concerning these iems. This is not a definitive review, as I generally don't do that, and I may provide further impressions later on with other sources.
In terms of context, I have been driving them with my AK240SS and then with the Lotoo Paw Gold, listening only to FLAC, Redbook and some 24/96. The Zeus I have are a demo provided by Jack, I just paid for the shipping. I will certainly be buying but we will come to that later.
Customer experience: I am not sure if my experience with Jack is the typical customer experience but it has been nothing but excellent. I have expressed interest in their product range and our interaction thereafter has been nothing but smooth and excellent. Jack had always taken all my comments with interest, trying to improve his products, looking for ways to address his clients' concerns. He visibly loves his products and his job, and it makes it really nice to deal with him.
Build quality and ergonomics: the build of these is excellent. There are very small for 14 drivers. It is a bit tricky to find the right tips, but once you have (spinfit medium or large for me), the fit is quite comfortable. A bit less than the 846, but more than the Roxannes or Solar. If I could note something to be improved, I think a more ergonomic shaped could be found, like the 846 or the Inear Stage Diver.
The cable provided is very nice, durable and flexible. I like more compact jacks but the right angled jack is still of great quality.
The whole iem fits in a very small case, so it allows for a very portable yet high end rig, paired with a high-end DAP.
Pairing and sensitivity: I will not insist on this, as I have said much about it already, but this is the only issue with the Zeus in my experience. It is twofold: the Zeus are not so easy to drive. I thought they sounded average of the AK240SS and significantly better out of the Lotoo Paw Gold. I am not sure if it is that they like more power, which would be counterintuitive for a very sensitive iem. The second part is indeed sensitivity, the Zeus hisses with my Mojo and my Paw Gold. I am starting to think know my demo is more sensitive than others, as some report no hiss with the Mojo. My Mojo has no hiss with my Solar, so the Mojo is not faulty. So to conclude I have not yet found a source that sounds good AND doesn't hiss at all. To be clear, the hiss on the Lotoo is very present, much more tolerable on the Mojo.
Sound quality: Once you find the right source, the Zeus is a marvel. It is quite colored, the mids sound pretty thick, I would say that it is because of a lift in the lower mids.
The key strong points are resolution and imaging. The sounds is quite forward and aggressive but it hits you in such an involving manner, all the layers are so fleshed out and textured, all the details can be heard perfectly placed in the stage, the mids are rich but refined, you can really hear the grain of the voices, making vocals very engaging. The stage is very deep, but clearly not at wide and airy as the Solar. It is not a negative point, because placement within that stage is very precise. Plus the quite narrow stage and lush mids allow a very together and centered sound. The Solar will have a more relaxed and laid back sound, placement in the stage is a bit more diffuse.
Bass is a bit north of neutral, highs are well extended but not aggressive. They have some sparkle but not the sparkliest nor the airiest if that is your thing.
On well mastered music, these are the most engaging and musical iems I have heard. I like them as much as my SE5 Ultimate. If I had only one I would keep the SE5 as it is more neutral, but I love the Zeus.
I am not yet sure which I prefer vs. The Solar, because on not so well mastered tracks, the Solars, being more spacious and airy, will sound better. Plus the Solar is much easier to pair source wise. But with the right source and goof quality tracks, I enjoy the Zeus more. The Solar are less fatiguing also, so for long seasons while reading for instance, I will go for the Solar. All in all these are very complementary.
Conclusion: I would love to see a less sensitive version come out, and maybe the signature is not for everyone if you like bright and thin sounding IEMs, but apart from that, the Zeus is a brilliant iem, standing above the crowd.