Complex sentence: Even though Korn was impressed by the work Ross Robinson had done on their previous albums, they decided to work with Steve Thompson and Toby Wright, although Robinson would work with Davis as a vocal coach for the album.
Split into simpler sentences: Even though Korn was impressed by the work Ross Robinson had done on their previous albums, they decided to work with Steve Thompson and Toby Wright. Robinson did however work with Davis as a vocal coach for the album.