Johnny Depp outside the Ed Sullivan Theatre for 'The Late Show With David Letterman'. New York City, USA - 27.07.06

The PIRATES OF THE CARIBBEAN star has performed in bands since he was 13, but the 76-year-old musical theatre legend fears his vocals may be too rock 'n' roll to play the murderous barber.

A spokesman for Sondheim says, "He wants to make sure that all versions of his works are the best possible."