Denny is one of those singers whose voice is so well know ( think "California Dreamin") but whose name is pretty obscure, I would think.
John Phillips had a knack of finding good singers. Scott McKenzie ( who had a huge hit with John Phillip's compostion "If You're Going to San Francisco") is another very talented singer who John promoted.
I loved Scott's first album. Great song choice. Great arrangements.
BTW, Scott performed with a later version of "The Mamas and the Papas"