I'm not orthodox but I truly enjoy listening to Russian orthodox chants. They evoke the depth and mystery of God's nature. Some of my favorite composers are Alexander Sheremetiev, Alexander Nikolsky, Nikolai Golovanov, Mikhail Strokin, Dmitri Bortnyansky, Alexander Grechaninov, Georgy Riutov, Piotr Ilych Tchaikovsky and Pavel Chesnokov. This one is from Pavel https://www.youtube.com/watch?v=03tuBNl9RAk