Time to revive the post with a consumer-type perspective.
Skipping what you think about XK Audio or what they did in the past, I managed to snatch a pair a while ago for 900 USD of XK Audio Serene (from Aliexpress). Now I see they are more like 1.7k USD on AliExpress, so apparently their value went up as well. They claim it is basically made to be like Susvara, but I never saw they claimed “this is Susvara” in branding.
I wanted headphones with such FR, and this seemed to be a fit for the ears, but most importantly for the budget. I mean, look at those FRs below and compare 950 USD, vs 8k USD headphones.
First thing, they are both produced in China, and as far as I know both are sourcing drivers, or driver related parts, from Chinese sources anyway. I think they developed these Serene headphones, apparently with the same or very similar drivers as Susvara. Frequencies match super close. And as far as I know, there is no such thing as counterfeiting a frequency response or having inspired design from different company (think of cover songs I guess).
I mean as a user of headphones wanting such headphones, buying over "legit" site like AliExpress, I do not understand all the rage around this specific case. I understand the part where they pretend to be some brand and literally copying whole design. That part is dishonest, of course, and I do not support it.
Perhaps they stopped with that, I guess, didint notice anything lately (perhaps for western buyers - maybe there is on taobao but that is chinese market and they have different rules concering these stuff anyway)? I do not know.
But man, look at the FR comparison graphs and the humongous price difference. As an audio consumer this is a freaking no brainer. I am extremely happy with my Serene, they are the real shit.
Good and sturdy build and all in all as a consumer (contrary to the original post) I can only recommend XK audio and Serene and for anyone wanting to save a buck to explore what they offer (unless it is literally a counterfeit - I do not support that).
I think XK audio should receive more praise and advertisement around products like Serene because it is legit good product. Maybe this could push them more into the territory to create something on their own, as obviously they have the capabilities to tune stuff and source good drivers.
P.S. They are (or at least my model) super duper difficult to drive. The cheapest all around thing that I have found to actually drive this properly is 22W (16ohm) output capable Topping A900 that I use to power them (I tried 8W and 12W @16ohm amp, but it wasn't giving enough headroom - which is amazing how hard at least my model is to drive).
P.P.S For anyone comparing batches or models of Serene. I dont know is this is serial number or production number or is it designation of the model. But only thing I have designated on them besides XK-AUDIO logo is No. 0017 (maybe someone can confirm do they have same No. on their Serene to confirm what is true regarding serial number, production number or just model designation). BTW nowhere on the headphones is written "Serene" - this is only implied with the advertisement from the seller (and the design of the headphones).