As a sound designer, i know what are you talking about.
1,The high gritty sound usually a chain reaction build up.. Many sampling engineers are not good recording engineers. They even have very low level sounding rooms and speakers.
2, Using bad digital eq-s in kontakt libraries, they try to make it sounding better but it ending with digital shizzle. So turn them of.
3. Try using low pass filters extensively on every sounds. The vintage samplers of sampling art was the low pass filter, and the nice dynamics. The ear does not like dry stuff loud above 10-15khz.

However, the problem with high strings hasn’t been solved till these days. Their equalization if fraught with enormous harmonic problems that are inbuilt to begin with. IMHO, there’s no best string library out there because they all have the same problem, namely, a suite of very high harmonics that cannot be cut without substantially, if not totally, altering their tone color. In fact, one is left with a synthy kernel, surrounded by a haze of white noise that I call sand paper effect (in German the term would be Schmirgelklang). If one only filters these parasitic noises (which are at the origin of grittiness), then one ends up with, well, gritty, discontinuous, uneven, sound. Some people equate this noise with bow noise, which I think is a mistake. For this reason I could not produce sweeping, dramatic melodic lines with high strings. I mainly write these kinds of lines, and invariably end up with bad sound. And, yes, the strings ARE in a much higher harmonic register compared to the underlining harmonic structure. Surely, one can write those minimalist ostinatos that pervade most all action scenes in that relentless, never changing E minor key, adorned with all of the articulations in this world. My purpose though is to write song-like lines. That’s hardly possible with the current libraries offered throughout the industry.

We’re constantly talking about mockups. Well, if we insist on using this term, then we’ll always get mockup quality samples. Why should manufacturers strive if there’s no demand for, yes, quality samples? Surely, from time to time, with great hype and exaggerated claims, industry will come up with new versions of their libraries. But, time and time again, I end up getting that bitter taste of raisin bran marketing theory. What did I just say? Well, sometime in the early ’90s, industry maven Louis Gerstner, then CEO of IBM, was answering questions at a press conference. He came from the cereal industry and answered the question in those terms. I cannot quote him exactly, but he said something like this: Now I am in the computer industry. It’s crazy. The rhythm of development and competition is absolutely maddening. When I was in cereal manufacturing, we put 4-5 raisins into a box and declared the product “new and improved”. You cannot do this in the computer industry. You’d sink in a heart beat.” Let me use this example as an analogy. I dare say that sample manufacturers kind of do the same thing. They build 4-5 new articulations into the library and declared it a new version. However, sound quality (I am talking here about high strings, the weakest link in general as far as string libraries are concerned) is hardly changed. This is the crux of the problem, IMHO.

Thanks for reading, J.