My .02.
For most of my adult life, (I'm 54) I listened on a cheap Sony boombox, which made me perfectly happy. I'm a music lover but paid absolutely no attention to how it was reproduced.
Along the way, I started getting mp3s that were in the 256 to 320 range, with the emphasis on the 320 end of things. And I could not tell the difference, at first. In fact, I still can't if you play me a short sample of music in both its 'original' form and as a well-recorded mp3.
But here's what happened to me: I found myself yanking the mp3 album after 15 or 20 minutes. It took me months to even notice I was doing it, and when it happened I had no idea why. (I'm not the brightest guy when it comes to such things.)
Anyway, that led me to read - and inevitably buy - and experiment. Whether it's my boombox or the tube amped full rangers in my family room, I can tell the difference between a cd and an mp3 copy with a high degree of accuracy if you give me half an hour with each. (Yes, with volume matching.) I will almost always yank the copy.
Now I had my hearing checked during all this, and I am in better shape than most guys my age, but I'd be willing to bet the younger people on the board could 'hear' rings around me, so I don't think this is a case of golden ears. I do think it may point out the real issue with lossy compression - not what it does in one instance or song, but in how you react to it over the longer haul.
Most importantly, this doesn't make me happy. I don't take any pride in being able to make the distinction, nor do I particularly enjoy it. It's a distraction, almost like an allergy - I listen for a bit and it just sounds...irritating.
Of interest, and what at first made me think it was all in my head - I can listen to radio, including online radio, for decent stretches of time without getting the same buzz, even though it's often the worst quality you can hear. I think a couple things are going on in that case: you downshift your expectations in the same way you would listening to a bootleg or a very old recording and more important, the fact that the music changes (you're not listening to the same artist/album all the way through) tends to mask the compression.
It's odd, but that's my experience.
Scott A.
Watertown NY