[stormmilk]

Fitear F111. Very close sounding to the ER4s, but slighlty more musical. A more enjoyable neutrality than ER4s imo.

Other than that Heir Audio 4.Ai is also tuned for neutrality and according to many reviews they are indeed very good.

Cannot agree with you more.

 

[Inks]

4Ai is anything but neutral and it's also received it's number of negative reviews. Personally, I found it awful...
 
Flattest? Believe the Apple in-ears but they have a distortion issue. LG HBS-800 is also extremely neutral, JBL tuned. 

 

[AstralStorm]

No IEM is really even, so the best you can ask for is the FR to be smooth and non-resonant, so that you can easily correct it.
 
For instance, InEar Stagediver SD-2 is only properly cleanly smooth when equipped with Comply, where you trade a lot of rolloff for the smoothness - which then has to be compensated with trivial EQ. Then it is truly top notch. (Ahead of the IERM.) It is behind UE IERM in highest end extension. Otherwise, it picks up some sort of blocked ear canal resonance getting exactly 2 peaks, taking the top position in universal IEMs too.
(I haven't heard jphonic IEMs, they might be comparable.)
 
Out of the box, I'd vote for UE Reference Monitor demo pair I've heard as the flattest - with some forwardness only and a trivial subbass and air roll.
 
(Considering the review, a potential candidate I haven't heard could be one of the higher end Custom Art CIEMs.)

 

[San Man]

I'll just leave this here:  Galaxy freq response provided by Sammy.

 

[AstralStorm]

The chart shows the measurement was done at a few discrete points and linear interpolation has been applied.
It's neither raw nor compensated nor smoothed in usual way with smoothing described. No idea what to make of it - it could hide any number of peaks.
 
Also Galaxy which?

 

[unknownguardian]

i do see the flat response up till the 2k frequency, i believe the boosted treble from them on is to make the iem more analytical. so with the boosted treble, is it still a neutral/flat signature? that is something i always ponder about.

 

[AstralStorm]

I suspect this is HRTF uncompensated measurement (other than being inaccurate on the whole), so the raised 3kHz region is mostly correct and will sound equal loudness mostly. Still, which Samsung earphones? They have magic letters + numbers naming scheme...
 
E.g. compare:
http://graphs.headphone.com/graphCompare.php?graphType=-2&graphID[]=743&scale=25 (raw)
vs
http://graphs.headphone.com/graphCompare.php?graphType=-1&graphID[]=743&scale=25 (compensated)
 
You see, the 3k rise in ER-4s which are forward sounding is quite a bit higher. (Specifically, ~6 dB higher referenced to 500 Hz. These Samsung earphones would sound bit V-shaped if anything due to the later 4-6k boost and 1 kHz cut.)
 
Nothing can be said about highs given that Samsung graph, which is either too few samples and/or massively smoothed other than perhaps being slightly rolled off. I'd wager these would sound somewhat like VSonic GR07 BE with lesser detail retrieval. (I have the model that was included alongside Note 3. They are pretty good but large shallow fit and not quite secure in ear.)

 

[Sam Edwards]

I have to say the KSE1500 is my new flat response champ, with the added bonus of incredible resolution.