The popularity of Take 6 led to collaborations with many, established artists. In fact, it was through Take 6 that Warren first met Quincy Jones, establishing a musical friendship that would last for decades. Take 6 performed on several songs and interludes on Jones' album "Back on the Block." In addition to performing with the group and contributing to their vocal arrangements, Warren is the featured voice on "Setembro (Brazilian Wedding Song)", and he penned the lyrics for "The Verb To Be (Introduction to Wee B. Dooinit)". Jones also invited Warren to be a featured vocalist on the song "The Secret Garden (Sweet Seduction Suite)." At the time, for personal reasons, Warren respectfully declined the invitation. Since then, Warren has characterized it as "one of the very few decisions in my life that I truly regret." In the years since, Warren has arranged, produced, or co-produced numerous songs for various Jones projects.