Listening to and comparing the Quad and 5.1 versions of this album again, I think I need to lower my vote slightly, giving each mix an 8. The 5.1 is a much more subtle surround experience, but presents the music in much better fidelity giving me the same experience I remember growing up, as I endlessly listened to my "24 kt gold" cd on headphones. The quad is fantastic in terms of discrete surround activity, but there are elements and fidelity lacking in the mix that make my enjoyment of the songs hit and miss. For example, the epic guitar solo in the second half of "Shine On You Crazy Diamond" is buried in the mix in the quad version, but really shines in the 5.1. The song "Wish You Were Here" in quad bums me out every time I hear it because of the missing guitar solo in the middle and the buried outro solo. Today I created my own "Frankenstein" version of the album that I can live with:
Shine On You Crazy Diamond- I used the 5.1 versions and merged them into a single 25 minute song. Epic.
Welcome To The Machine - Used the quad version but made some tweaks including adding an LFE channel so the room rumbles during the "machine" sounds (my dogs freak out, lol)
Have A Cigar - Used the quad version- perfect as is
Wish You Were Here - Used the quad version, but spliced in the guitar solo sections of the front channels from the 5.1 Guthrie mix
Edit: On second thought, I'll leave my vote as is... getting 2 good Floyd mixes on the same disc deserves a bump to 9