I was lucky enough to work in audio mastering, for almost 2 decades. As such, you have to develop an ear, that is capable of hearing differences in quick A/B comparisons. So, when I hear differences in gear, or burn in, or levels, or whatever, it's usually something to it. Especially since I could capture and compare samples of audio, in my workstation, and invert one sample, to hear if the 2 combined wave files cancel each other or not? If not, there was a true difference, regardless if the difference could be explained or not? Client's hated that too, especially if their clamed differences turned out to be listening differences between their own set up's, and their mastering engineer's. Nothing we did during replication.