On my previous visit to my favourite Hifi dealer, we talked about to which extend doing things like MP3 compression to your music ruins it. While even I can hear that low quality, say, 128 KBit, MP3 files (which iTunes ironically calls High-quality, as compared to Higher and Highest) aren't the same as the original and may even sound wrong, the question remains what happens with higher quality files and whether you can reliably detect the difference.
As I had to pick up something there anyway, I prepared a little CD containing two songs (The Man Comes Around off Johnny Cash's latest CD and Parce Mihi Domine off the Officium CD by Jan Garbarek and the Hilliard Ensemble, which is contained in my nice new CD set) in six versions (full quality AIFF and 320KBit, 256KBit, 192KBit, 160KBit, 128Kbit MP3) each. I left it as a little challenge for him to figure out the order of the qualities and I'll see how he did the next time I come over.
While I am with people claiming to hear the difference between quality reduced music and the original versions and I am eager to learn how to figure out the more subtle differences myself the other topic that arose was the - alleged - difference between a CD and an identical copy thereof. I don't think there should be one and can't see why there could be one. Also, I was never able to hear a difference - yet. So we're in for another test I guess and I'll bring some copied CDs, asking him which one is the original and which is the copy. In the meantime I'll remain curious and take any hints on how there could be a difference.
Received data seems to be invalid. The wanted file does probably not exist or the guys at last.fm changed something.