When I arrived in Sheffield, the musical director, Jeremy Sams, met me at the stage door and took me to a dressing room. No piano, but that didn't seem to bother him. I talked a bit about what I had done at college, then asked if he wanted to hear me play. "No, it's OK. You won the same prize that I did, so I know what standard you are. You've got the job".
And I hadn't played a note to anyone.
Also check out Jeremy's Vocal Process website with many useful articles on singing, pedagogy, and computer voice analysis.