Rob Schlette, writing for The Pro Audio Files:
The topic of audio perception has been pretty hot lately. From the popular news media coverage of Mastered for iTunes to the pages of TapeOp magazine, it’s not uncommon for people to be asking the question, “Can you really hear the difference?†This is very good news for music and music lovers.That might not seem like an extraordinary question for people to be asking, but the elastic reach of hardware and software marketing nonsense has devalued sensory feedback. We are routinely exposed to the most outrageous qualitative claims that have never been proven (or even suggested) with a marginally systematic listening test.
He’s right. The question, “Can we hear a difference?” shouldn’t be extraordinary or controversial in any way. He goes on to write:
I’ll bounce the same audio source twice—once with each codec product set to identical digital audio precisions. Absolutely nothing else about the two bounces can be  different, or the test is pointless. If I’m really being honest, I get someone else to load up the examples into the tester app so I don’t know which is which.
I’ll go further and say that the only way to do a proper ABX test is to have someone else load the examples into the tester app (or better yet, create a tester app that randomly assigns the examples. Are you listening, Takashi?). Or better yet, have one person load the examples, then present the test to another person who doesn’t even know what they’re supposed to be listening for.