The robust build quality of the IV-4S got me interested to try them. Unfortunately, I received a defective pair. Judging by the right channel (the faultless one), the bass is mostly distorted while vocals sound harsh and shouty. I wouldn't recommend these earphones to anyone, unless I hate them very much.
Again, this is a sad occasion where you get a very unique build quality, but poor sound quality.
The mids and highs sound very crisp and detailed.
Very solid build quality, as usual with the Ivery's IV series.
The included accessories are pretty nice.
The lows sound distorted, while the mids/vocals sound harsh a sibilant.
A lot of static noice when idle.
Very poor QA (quality assurance). The left channel is defective.
The included foam tips aren't made of memory foam.
Package & Accessories
Ear Tips - Single-Flange:
S+M+L, grey (translucent), ?5mm red bores
Ear Tips - Foam:
Faux foam, red, ?4mm bores
White, 360° cable holder, generic
Leatherette, black, branded
Build & Materials
Metal, ?5mm nozzles, soft strain reliefs
Metal, no strain reliefs
Silicone-coated (smooth), soft, mildly bent
Metal, straight, short, no strain relief
Comfort & Fit
They fit really good with the pre-applied tips. They aren't bulky and don't fall out easily.
Lows / Bass
For the defective pair I received, I can only say that the bass is present, but is very poor and distorted.
Mids / Vocals
The vocals are somewhat quiet, but from what I can gather, they seem to sound quite decent. Slightly harsh, slightly sibilant, but overall not that bad.
Highs / Treble
There's a noticeable peak on the defective channel that cause huge sibilance. That probably doesn't happen on a properly working pair. Judging solely by the non-defective right channel, the highs seem a bit harsh but overall decent.