Agree with you. NaCl taste different from different supplier as well. Although all are NaCl but because of the way the NaCl are created/mined/purified, it gives a totally different taste. for copper although all are Cu, but they can be very different resulting in different conductivity and different sound. https://www.sciencedirect.com/science/article/abs/pii/S092150932500142X#:~:text=Abstract. Single crystal copper exhibits superior conductivity,in the field of electronic information transmission.
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Thanks for your cooperation.