As I said, this goes both ways--I can't sing much Elvis in Elvis's key. Elvis was a baritone. I used to do "It's Now Or Never" and I'd have to raise the key three steps. Same with a lot of Sinatra--most of his stuff is OK, but the bottom of his range is lower than I can go. If you think of the song "I've Got You Under My Skin"--when he sings the title at the end of each verse, I can't hit the 'under my skin'. To sing that song, I need to raise it a couple steps to hit that passage. And, in his key, when he goes 'up'--the second pass through "Every time I do just the thought of you makes me stop--", that's in the middle of my range. I could raise that part close to an octave and still hit it.