The challenge behind some of that cork sniffing is the differing behavior of "identical" circuits is often trivially measurable and audible. Many of the "rever

The challenge behind some of that cork sniffing is the differing behavior of "identical" circuits is often trivially measurable and audible. Many of the "revered" circuits perform very differently due to component variations (e.g hFE or Vgs), and also have substantial drift in performance with temperature. So even different units from same manufacturer will sound different.