Oswald's "Plunderphonics" essay is full of all sorts of interesting details that I've been chasing all week.
Here's a piece by James Tenney from 1961 called "Collage #1," a deconstruction of Elvis' "Blue Suede Shoes." Oswald uses it as a defense of the cut and paste—in this case, literally, as Tenney worked with tape and razors—invoking Milton, Stravinsky and the moral and legal high road:
"Piracy or plagiarism of a work occur, according to Milton, 'if it is not bettered by the borrower'. Stravinsky added the right of possession to Milton's distinction when he said, 'A good composer does not imitate; he steals.' ...My observation is that Tenney's "Blue Suede" fulfills Milton's stipulation; is supported by Stravinsky's aphorism; and does not contravene Elvis' morality or Section 17(2)(b) of the Copyright Act."