Some links on loops and art installations...
The San Francisco Exploratorium installation had a soundtrack that consisted of loops of varying lengths, on auto-repeat cassette decks playing non synchronously. So he had four cassette decks playing different length loops in 8 different channels (as far as I could tell they were not "stereo" mixes on the tapes but actually two different non-synchronous tracks), and then he localized the channels through speakers scattered through the installations so standing at any one spot you would hear a blend of loops through different speakers. These "loops" were actually fairly long, and the "soundtrack" itself was essentially one huge loop - Eno guestimated that it would take some 127 weeks for the loop to precisely repeat itself. But from a listener perspective repetetive elements were pretty recognizable. It sounds like Eno may have used the same source material at various locations, but each random configuration of the starting of the cassettes would create a fairly unique juxtaposition of the source loops.