Right after I've posted, they arrived.
I've ended up paying tax to the delivery guy as well. So, this is sth new but anyway not that related...

OOTB, I like what I hear and I don't hear mid bass bloating to the mids. Very energetic set of IEMs I'd say. It has a great synergy and coherence. Mids are nice for both male and female vocals, lush.

I don't agree with BGGAR's graph for the bass part. However, I agree with his graph when it comes to treble because there's a peak at 10k definitely, causing slight sibilance.
Piezos do their job well and it's really airy, ultra high ends come with good resolution.
The cable and accessories are bad. I immediately hear the difference when I change the cable to a third party one.

These guys sounds different with every cable and set of tips. So, definitely try them with different options.

The soundstage is good with a well distribution on three dimensions. Different cables effect the depth of it. Some makes it deeper with narrowing the width. The timbre is good and overall tonality is done well considering that these guys using 4 actual different type of drivers.
They don't need amping amd sound fine with every device I used. I don't even hear any hiss from my dx160's 3.5mm. Not even with high impedance...
I'd say one thing. This is not bu..s...! These headphones definitely hits well above its price range. It can easily compete with the ones above 100$. For example, I'd take GK10 over Bqeyz Summer. Mids are great with GK10. GK10 is not that harsh in the treble part. Bass is better on Summer, but, I'll give some time to burning the GK10 and see how it goes as the Summer is already above 100 hours.
Comparing to LZ A7, well they're definitely not in the same class. LZ A7 excels over the GK10 in every aspect, maybe the bass is not that strong on A7. However, switching from GK10 to A7 doesn't reveal a day&night difference, I don't hear a price 5-6 times price jump. So, I understand what Dsnuts meant.
Folks, let me say that I'm surprised and more hopeful at the the same time that a set worth of 45$ can deliver that SQ. These sets can be end game for some having difficulties buying an IEM even over 50$ price level...