There is a cd + dvd-a version of King Crimson's 40th Anniversary edition. The cd has the 2009 mix plus 5 bonus tracks. The dvd-a has 2 surround formats plus the 2009 mix in 24/96 stereo and the 2004 mix in 24/48 stereo.
The reason for the remixing is that the album was originally recorded on 4 track tape and they had to "bounce down" the recording (rerecord two or more tracks to one track) to get more than 4 tracks worth of music. Therefore they couldn't change the mix on an individual instrument and they had to use second or third generation tapes for the mastering. For this edition they were able to go back to the first generation "slave masters" (pre "bounce down") that contained the one instrument per track original recording. Steven Wilson worked closely with Robert Fripp on the new mixes, according to the liner notes.
There is also a 5 cd + dvd-a version if you really love this album.
