I don’t think you understand what the placebo effect is. This effect operates when people are in expectation of something, and there imagination works to fullfill their expectations. E.g., you give someone a sugar pill but tell them its a pain killer, and they will think it has an effect because they expect it to, even though it is only sugar. The key to this effect, which you are missing somehow, is that the person is conciously aware of the expectation.
In the case I outlined, I was unaware that I had put the mp3 card i, as I did this by accident. Therefor the placebo effect could not be happening in this case. I had no pre-conditioned expectations. This shows the accuracy of my analysis - I could really hear the difference, rather than imagine I had.
For the placebo effect to have happened in this case, I would have to have known that the mp3 card was in the player, thus conditioning my expectations - its mp3 so I expect it to sound bad. In fact the more classic placebo scenario would have been if someone had told me they put in an mp3 card, but in fact put in the wma, and I said it sounded bad. Thats placebo.
I do not hold these ab comparison in any regard whatsoever, primarily because they ask the subjects to conciously do something that is in essence unconcious. When you listen to music normally, you do not try and conciously analyze it while you are listening. Its an entirely automatic and unconcious process. To be able to compare music in a concious way assumes that the concious part of the brain analyses music the same way that the unconcious part of the brain does - and of course it obviously does not.
In an a-b comparison you can do crude things like ask “is there more bass”, “does the drum sound a bit louded”, “was the cymbal on the previous recording a little bit cleaner”, and other rather crude and simplistic things. But it is almost impossible to compare things like “when the singer sang that phrase, did it sound sadder”, or “did the guitar solo sound more aggresive”, etc. These more complex emotional things and others which we cannot even know about cannot be conciously weighed in your mind.
Its like comparing the faces of beautiful women - you might be able to state which one has a longer face, or which one has eyes that are closer together, but ask “which one has the most soulful looking face”, or “which one has the most reassuring looking face”, and just where do you begin to analyse those kinds of questions?
When you listen to music normally, the brain works in an entirely automatic fashion to process the music, making emotional connections amongst many other things, and I do not believe this is the same kind of thing that happens when you do an a-b comparison. You cannot subject something as subjective and emotional things as music to a scientific anlaytical analysis.
The fact that people in a typical a-b test cannot tell the difference between two sources does not mean they are the equal - it simply means that they cannot, under those, circumstances tell the difference. Normal listening is very different to an a-b, where you are saying to yourself “hmm, did that second one have just a bit more treble”, or “I think that cymbal sounded a little more tinny”.
The unconcious mind exmaines music in much more detail than this, details that the concious mind cannot even begin to know about.
My advice, forget these tests, and go by how much you enjoy listening to the music.
Indeed it is in your head - thats where you “listen” to or “experience” music.
I know that I can, and indeed have done, a-b comparisons where i cannot easily tell the difference between an mp3 and a wma. But I also know that if I spend a day listening to a wma encoded version of my music, I enjoy it, and if I listen to an mp3 encoded version of my music, I either don’t enjoy it much at all or enjoy it much less. As I said above, being able to tell the difference between two recordings in an a-b comparison and normal listening are two totally different things.
As to becoming more knowledgable about music, I am 55 years old and have been listening to music through various systems, including a lot of high end equipment, for most of my life.