Do a ABX test, AAC 256, absurd to say one can hear the difference. The placebo effect can play big mind games one must do an ABX .
Actually, it's absurd to categorically say that no one can tell the difference. I'm not an idiot. I know what the placebo effect is and I wouldn't have spent the time/effort/money on maintaining a lossless audio collection if I couldn't tell the difference. I have a pair of JH Audio headphones for work and a much, much more expensive home audio setup at home. On that hardware not only can you hear the difference, it's apparent. If someone comes over and plays an MP3 cd or something on my system it sounds noticeably "off". That's because the speakers can reproduce a much wider range of frequencies and you can hear the clipping from the compression.
Most people don't care about sound quality and won't spend more than $100 on headphones anyway (hell, most people just use the stock apple earbuds). If that's you, great. To each his own. All I'm saying is that some people, like myself, do. Don't fault us for wanting actual high quality sound on our music devices.