What's the definitive version of a song? Is it what's on the sheet music? Is it a particular performer on a particular night who pounds the plaque away from a musty and hoary standard? Is it encoded into 24bit FLAC to digitally shine from your hard drive indefinitely, so long as FLAC sticks around as a format? Is it a relatively untouched German pressing of a vinyl album? Does the concept of "definitive" even exist, said the psychologist focused on the subjective glamour of perceptual parameters? Many of the above questions ran through my mind recently, as I opened up the 2-CD/2-DVD "bookcase" version of Aqualung , the classic 1971 album from Jethro Tull. In this bookcase version, you get the following takes on Aqualung : A 2015 stereo remix by contemporary prog god Steven Wilson (Porcupine Tree, Blackfield, Storm Corrosion, etc.) A flat transfer from the original stereo master in 96/24 LPCM stereo A 2015 5.1 surround remix in DTS 96/24, AC3 Dolby Digi