[OT] Trivia: What is this composition called?

[Rainer Straschill <moinsound@googlemail.com>]

I'm addressing this knowledgable group with a question about the
composer and titel of a piece of music which I can only describe in
its concept.

You have several musicians sitting in different rooms (meaning: they
can't hear each other). They are told to play something. Each musician
is then miked and the signal fed to a central mixing console.
The guy on the mixing console has to mix the individual parts
together; however, he is not enabled to listen to them. The
performance is then what comes out of the console.

Anyone remembers this piece and can tell me title/composer. I have the
distinct suspicion that it was Cage, but am not so sure...and have no
clues about the title.

Thanks,

              Rainer