I find it interesting that not many people know who Alan Parsons is, but I'd say 95% of the world has heard his work. He was an audio engineer on The Beatle's Abbey Road, and also Pink Floyd's Dark Side of the Moon. There were plenty others, but I think those are probably the two most notable. Pyramid is a very experimental studio album, featuring 15 or so different vocalists through the whole album. He worked with Eric Woolfson to try and create a new type of album. Their goal was to not put excessive focus on individual musicians, but to highlight the production and composition of the album.