Just received a review unit for the NiceHCK EBX 21. Will be passing it on to another reviewer at Audioreviews after a spin with it.
As befits its TOTL namesake, the NiceHCK EBX21 comes with very nice accessories, including a nice carrying case, a multitude of covers (full foams, donut foams, silicone rings). The cable comes with a magnetic clasp too.
So this is one TOTL earbud that has a detachable cable, unlike some of its TOTL brethen that are still stuck (no pun intended) in non detachable formats, which may be a potential source of failure down the line. During ordering, you can choose whether to get a choice of 2.5 mm or 3.5 mm or 4.4 mm termination. I know there's some hoohah that the cable itself is selling for 100 bucks or thereabouts, but FWIW, the cable is very impressively braided and supple, one of the best cables I've used in a haptic sense. It comes with a chin cinch, and the MMCX locks quite satisfyingly with a click.
The NiceHCK EBX21 can be worn cable up or down, depending on your ear anatomy and preferences. Fit is very comfortable and light.
It is very easy to drive as per its very high sensitivity. I was actually expecting it to hiss like a snake due to the high sensitivity, but surprisingly there wasn't much hiss.
OOTB impressions: quite a neutralish tuning. Very smooth with minimal peaks/troughs in the tuning, yet managing to maintain lots of microdetails. Quite a few CHIFI earbuds and IEMs do "cheat" by boosting the upper mids and lower treble to get more clarity and a sense of perceived details, but here, you can really tell the EBX21 manages to get the details in without cranking it. Imaging, clarity, soundstage and instrument separation are really top notch, definitely the best earbud I've heard in terms of technicalities. It can keep up with fast portions or complex portions of music with no congestion or issues. I daresay it has resolution approaching some multi driver IEMs, no easy feat for a earbud.
In terms of the bass, this set is midbass focused. Midbass is neutral, subbass is unfortunately rolled off like most earbuds, both in terms of quantity and extension. So the SMABAT series earbuds will still beat this set in terms of absolute subbass amounts/extension. Bass on the EBX21 is very textured though, and of high quality, with no midbass bleed. Bass accuracy and speed are good. Mids are transparent and very detailed, with no harshness at the upper mids. Vocals are very clear yet not shouty. Treble extends moderately well, and is pretty good for a earbud. Sibilance is very mild, and cymbals and highhats sound very natural with no splashiness.
Timbre on this set is excellent for instrumental timbre and vocals. Vocal lovers and those who like acoustic instruments will enjoy this set.
So I think this earbud really lives up to the name of TOTL sound, in terms of the 3 Ts of timbre, tonality and technicalities. If only it had a bit more subbass extension (like the SMABAT series earbuds), then I think the tuning would be perfect. The cost is also quite high for this set, and diminishing returns do exist especially for earbuds, but this is probably endgame level for earbuds.