http://mixonline.com/mag/audio_surround_revolution/
“Musically, I want the stereo and the 5.1 to be compatible,” he continues. “I want it to be the same mix in terms of the balance of the voice and the guitar and all those kind of things. I don't want to go to the surround mix and all of a sudden there's a completely different musical picture, particularly on a live recording. At the same time, you can do a lot more with ambience and audience in the surround mix. Normally, with a live show, you do a lot of audience mic riding, because there are definitely times when it's appropriate to hear more audience, but when the focus is really on the music, you want to bring those mics down so the music doesn't get muddy. Mixing in surround, I find that I want to keep more of the audience and hall ambience up the mix can take it because there's more coherency as the ambience is spread out in four or five speakers, as opposed to two. A similar effect can be observed by recording a lecture in stereo from the back of a hall if you listen in mono, you'll find it much harder to make out what is being said than in stereo. I double-patched the audience [tracks] to two sets of faders, so I had one group for the stereo and another for the surround. I would ride them separately and bring the stereo audience down more often and more drastically. In the surround, the audience is up a lot more often, especially the rear channels, because all that's really back there is ambience and audience. I did spread the piano out a bit on the right, and I think the organ is sort of between the front and back on the left.”