I'm not sure what the Everly Brothers were considered but I remember them from a very long time ago when I turned a teenager in 1959. Just some months ago I found out Phil Everly had passed away early last year due to lung problems. They were superb and probably the best on line video you'll ever see of them was back in 1983 when they got together after a long separation at the Royal Albert Hall. Some here may have seen them...wish I could have. I suppose I've never seen them any better than what this video had to offer. Liked it so well, I bought the DVD.
https://www.youtube.com/watch?v=pCdp3neIDO4
https://www.youtube.com/watch?v=pCdp3neIDO4