I've owned the HD381F for over 4 years now, and despite recent leaps in the Chinese earphone market (e.g. KZ, Xiaomi, Chinese earphone thread on head-fi etc.), the HD381F remains one of my favourite low-cost earphones.
I would say the sound signature is very balanced and natural, but the bass is more mid-bass oriented instead of sub-bass. The highs are not peaky like a lot of V-shaped earphones, and it isn't too smooth as well (my Noble K10U sounds darker).
The two cons I have with this earphones are: 1. Construction - while my pair still works perfectly fine, they feel very cheap. 2. Isolation - I think these are semi-open, but whatever it is, isolation is definitely not great on these earphones.
I originally bought these to replace my lost Apple Earpods until I could afford something a little higher end. In the box is the earphones, an extra couple sets of tips (the preinstalled tips were fine for me) and a weird looking clip... didn't really figure out the use for that but the packaging was good enough for the quality of the earphones. This particular version of the 381's is the flat response version, and honestly I thought that's what I wanted, but I think I would have been happier with something a little bass heavy.
Of course this is no fault of the earphones, they are flat as the description says but it's just preference at the end of the day, so I'd recommend checking out the other versions of the 381's to find the one that best suites you.
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