[Sevores]

Also worth mentioning Terre Thaemlitz, who wrote a nearly 30 hour piece with two chords.

"The resulting MP3 file is an edit of a 31+ hour piano solo recorded in sittings averaging 4 to 6 hours in length. The theme is "Meditation on Wage Labor and the Death of the Album.""

You can listen to an excerpt here: http://www.comatonse.com/writings/2012_soulnessless.html#c5

And here's the sheet music: http://i.imgur.com/DoD1Ew4.jpg

[ajnin]

All sound samples on the page start playing at once when visiting it. A bit disconcerting but I guess that counts as involuntary experimental music in itself.