Geeky blog post for the techies out there ... found this interesting graphical comparison of the various audio encoding formats. Most of this stuff is common knowledge to studio engineers, but I'd never seen it represented in this way before.
All graphs taken from & fully explained at the URL below:
http://www.stereophile.com/features/308mp3cd/index1.htm
Original test / audio signal:
Test signal encoded using FLAC:
Test signal encoded 128kbps MP3:
Test signal encoded using 128kbps AAC MP3:
So next time you download a song, you are only actually getting the gist of it. Make the effort to hear the whole thing. It's the same as looking at a massive painting scaled down a 10% quality JPEG or drinking fine wine mixed with 90% water.