Ritteri, I am glad that your experiences have been educational (education is a beautiful thing); and that you have had the opportunity to take part in these "controlled tests". However, the best education is attained by accepting the fact that there is always more to learn. Just because you don't hear the obvious differences between real and recorded, does not mean that the differences don't exist, and that they are not obvious to others. To make comments like "violins are not difficult to record/reproduce because their audible spectrum lies in the midrange and above", simply weakens your case. I guess this means that female vocals, trumpet, clarinet, flute are also easy to record. These have a range even narrower that the violins , but still in the "midrange and above". When digital recordings first came on the scene, and even today, guess what it was that most listeners objected to about their sound? The sound of strings. Anyway, the idea that one instrument is easier to record than another is, overall, simply absurd. It's a bit like saying: the trumpet is easier to play than the oboe. Not true, they are all difficult to play and to record well; overall, to the same degree. We all focus on different aspects of sound, and deem easier those that we are more confortable with.
Happy listening.