DJs Spinning Those Hard Drives
Mipmap writes "Ben Kirkendoll leaves the records at home in favor of his iPods, Apple Computer's disk-based music player, which he simply plugs into an audio system's mixer. He's part of a small but growing number of DJs who have turned to MP3 music files for their accessibility and convenience..."
At the very high sound levels in clubs a human ear cannot distinguish any longer between the high frequency pitchs which would be affected be low quality encoding.
Additionally the standard audience of a club is usually exposed to high sound levels over longer periods therefore having a reduced ability of hearing these high frequencies.
BTW: This also affects the DJs, you can check this by making a spectrum analysis of the standard techno/club stuff on MTV. You'll notice extremely repetitive/monotone patterns in the high frequency bands. This is were the club saying: "I'm addicted to bass" comes from.
Owner of a Mensa membership card.