The great composer Arnold Schoenberg once wrote of Nyiregyházi, in a note to Los Angeles Philharmonic conductor Otto Klemperer, “Such power of expression I have never heard before. … Technique: it is astonishing what and how he plays: one never has the sense that it is difficult, that it is technique at all, but rather that sheer force of will permits him to surmount all difficulties in realizing an idea. — You see I'm becoming almost poetic.”