One of the participants in this event has just sent me a link to a soundfile of the entire group improvisation directed by Urs Leimgruber.
http://soundcloud.com/jonathansielaff/urs-large-ensemble-cmg
Enjoy!

Barney Childs died of Parkinson’s disease ten years ago in Redlands, California. Although an important figure in contemporary music, Barney was in no way a self-promoter. I don’t remember hearing any of his music at concerts of the Redlands New Music Society, which he ran. At a weekend series of concerts later that same January [...]