Speaking of scores... From the South Florida Classical Review:
For most of his lifetime, Charles Ives was regarded as something of a benighted crank.
The Danbury, Connecticut, native was successful in the insurance business, but little of his music was known or performed while he was alive. In the 1950s and, largely, after his death, Ives’ stupefying originality and the innovative, experimental nature of his music were finally recognized when he was championed by Leonard Bernstein and others.
And then this:
In addition to requiring a pianist who can handle the fusillade of notes, the sonata also calls for a flute in the concluding Thoreau movement, and, in some editions, a viola in Emerson, which Denk believes is a too-literal misinterpretation of Ives merely asking for a viola sound. “I don’t think even Ives was perverse enough to put a viola in a piano sonata.”
Here's some from Ives.