Well, presumably this phenomenon has been tested in the hands of professionals who play violins every day. A pro will own several instruments, for example, many

Well, presumably this phenomenon has been tested in the hands of professionals who play violins every day. A pro will own several instruments, for example, many of which will be in storage. Having said that, your point is very real. I find it hard to believe that it's easy to conduct a double-blind test of violins. Violinists are not robots. Put two different violins into their hands and they will notice a difference, and their playing will change. Can you really set up two violins to the point where even a blindfolded violinist, feeling them under the fingers, can't tell when you swap one instrument for another? Same size and shape? Same string tension? Same feel of the finish on the neck? Same bridge placement? Same tension on the tuning pegs? As you point out, even the sound of a piano is acutely sensitive to subtle differences in playing style, and a piano's sound is much more constrained by its design than the sound of a violin.