In Through The Out Door, the eighth and final Led Zeppelin studio album is 1 that has been called Zep's prog album as the band used keyboards and synthesizers on this album that they never had done prior. The opening track "Carouselambra" is a vivid example of the way guitarist Jimmy Page and vocalist Robert Plant were willing to try a different style of rock on the album, i.e. move away from just the hard, guitar-driven rock sound they'd played to perfection on their previous studio albums.