received GUCraftsman cables.
my intuition was right, as usual (at the end, it works better than my logic, although intuition starts from a logic filter probably).
[click on pics for detail]
they have measured (dc resistance, L+, R+, L+, R-, in mΩ; and weight, including plugs and strap):
he400i copper 142 143 133 135
mmcx copper 136 143 127 130 (26.85g)
mmcx silver 135 133 124 128 (27.5g)
so they are definitely 8 cores of 0.08mm*19strands (equivalent to 27awg per core), PVC sleeved. the cable is equivalent to 24awg per signal (2 cores). quite good conductivity, while keeping good flexibility ad softness (they aren't so flexible and soft than some thinner wires).
i've tested them. xduoo x20 balanced with toneking t4, and zishan dsd ak4495 + ghostaudio miniA1 amp + he400i (single end).
when compared with 7n occ thicker cables, after trying hard, i barely notice any difference, which is great.
when compared with stock HE400i cable.. oh, man, the difference is quite noticeable: this cable respects headphones resolution, less distortion, cleaner sound. amazing.
everyday i listen to and compare cables, the more convinced i am about the difference consists mainly in distortion. i must measure this asap..
when i saw these guys use the same wires for all their hand-crafted cables, i supposed that they chose their wire carefully. so the wire must be true 6N pocc, as claimed. my ears also do believe it, after comparing them with my best cables (7n occ and so). manufacturer says that silver wire is "pocc single crystal silver" (not silver plated copper). hope to confirm this with measurements.
i'd go silver for warm phones, and copper for thin ones, but i couldn't hear a conclusive sound difference between them. maybe silver sounds slightly thinner. or choose by aesthetics criteria..
the presentation is awesome: the box, the bag with their logo/ideograms.. i'm in love with the y-divider and chin slider (which is tight, it doesn't slide by its own). they are made of some metal, the shape and text remind where they are made in (i think they've chosen it very well: the size, shape, and text). the look is superb. you can choose with or without ear guides (thermoplastic). you get an exclusive unique hand-made cable. the only but i found, is i'd like a longer/softer/progressive strain relief in the jack.
and essential: these guys are very communicative, enthusiast, love their work, provide every info you ask for, solve issues easy, can make custom cables (i'm going to order a ATH-M70x cable, not in their shop inventory, to them), and are very efficient, kind, and cordial. highly recommended. try to get advantage of last promotion day!
i'm very happy with the result.
some more pics (
color of the copper cable is darker than in these pics; color of the silver cable is shiny grey, or who knows.. did i mention i'm color blinded?), including a gift: alo audio balanced to trs adapter (nice one!):
mmcx copper:
he400i copper:
(good strain reliefs here; below the transparent part, a more rigid part is colored red/black, to differentiate sides)
mmcx silver:
Edit: forgot to add links (before starting to receive PMs asking for them..)
https://www.aliexpress.com/item/-/32887680475.html
https://www.aliexpress.com/item/-/32887728749.html
https://www.aliexpress.com/item/-/32889002978.html