Knowing @rhythmdevils, he would like a few db less uplight in the upper mids than Crinacle target. He's preferences are very similar to mine, probably exactly the same, except he he has much less tolerance for bright shit or peaks, even if narrow. I can deal with a bit more bumpiness. @rhythmdevils appreciates smoothness. I'm in agreement with @rhythmdevils that the Gaudio Nair is the neutral standard. That being said, IEM frequency responses are more or less fubar. That is they very seriously Fucked Up Beyond All Recognition and thus don't have as good a correlation of what is heard compared to headphones. The problems are several fold: IEMs have zero interaction with pinna and cocha. They bypass these structures. The inverse transfer function for the ear done by the brain for one individual's pinna and chocha will be different from another. Thus the perception of frequency response can different quite a bit from 2-7kHz. Tips and insertion depth, will be different from person to person, and especially to an artificial coupler. Approaches to IEM driver selection, crossover design, acoustic chamber design, filtering, are more complex than that of headphones. This can result in much more varied distortion characteristics than seen with headphones (dynamic, ortho, or e-stat). Because of nonlinear distortion throwing a wrench into the works, frequency response becomes less useful for relative comparisons of perceived tonal signature. A good example of the above is the PP8. The PP8 according to Crin's plots have almost exactly the same FR as the Gaudio Nair. I found the PP8 to be rather difficult in the upper mids and slightly lacking body in the lower mids when compared to the Nair. I would also be 90% sure that @rhythmdevils no like PP8. FWIW, here are my Nair vs PP8 FR measurements.