I think the piece is nice but the melody stays always in a percussive high register; some contrast would be good, I think. it all depends on your intentions.
Quoted from Wiki:
"The piano is prepared by inserted coins between the strings in its upper register as well as being electrically amplified creating a ‘church bell’ sound".
So the "amplifier" refers to the electrical amplifiers.
But the source is in a book and I have no access to it.