As I promised, here is a duet with Peter Hollens and Jackie Evancho. Peter did a stunning performance of this song, simply singing all the parts himself. In this case, though, although it is still acapella, Peter is joined by Jackie Evancho. Her dynamic and powerful soprano voice makes the song a stunning rendition.
What is even more powerful is that she was only 14 when she performed this song with Peter. I could say something about how well Jackie belts out the song, but truth is that both Peter and Jackie merely open their mouths and the music flows out. Nothing at all is forced. That is the sign of a true singer.