The only thing I can offer is perhaps the EMC uses a form of digital processing to smooth out very sharp high frequency transitions. In most cases this would create a more "analog" sound--smoother and warmer. It would get rid of that high frequency harsh (or is it hash) sound. However, you may have found a disc that is on the threshold of the EMC interpreting that sharp gradient of the string pluck at a high frequency to some form of digital noise--and it's therefore filtering it out--to protect you from that cold harsh digital sound.
I really have no idea about how the EMC actually does their digital processing--so I could be entirely wrong--but the concept seems plausible. And I'll pass on the chocolates--even if I'm right--but thanks.
I really have no idea about how the EMC actually does their digital processing--so I could be entirely wrong--but the concept seems plausible. And I'll pass on the chocolates--even if I'm right--but thanks.