Singer Cassandra Wilson joins Vandross on "I'm Only Human," a slice of jazz that follows in the duet tradition of such Vandross classics as "There's Nothing Better Than Love" with Gregory Hines, "If This World Were Mine" with Cheryl Lynn and "The Best Things in Life are Free" with Janet Jackson. "A lot of people have thought that I'm singing with another man on that cut," Vandross confides with a chuckle. "Her voice is pretty low on there, isn't it?" But despite all its collaborations, I Know is very much a Vandross affair. "I've had many R&B Number Ones," Vandross points out. (He's had six singles and seven albums reach that pinnacle position, as well as four Top 10 pop singles), "But I've never had a pop Number One. In the past, there has been a lot of pressure placed on me to team up with the latest, hottest hitmaker and that's to be expected. But I want that Number One Pop record on my own achievement. Then I'll be working with other producers." Vandross' own personal favorite track on I Know is the ethereal, magical "Dream Lover," a languorous mood piece that tells of an amorous apparition that makes its way to his dreams every night and leaves as he wakes. "The way that track is played, together with the voices of Cissy Houston, Tawatha Agee, Paulette McWilliams, Cindy Mizelle and Brenda White-King in the background-- it's like Matisse set to music." Most best-selling musicians experience a moment of great success when their initial style matches the public's taste, then struggle to adapt when the public moves on.