The most humbling aspect of The Manhattan Transfer's international ­popularity is that its members initially counted themselves lucky just to have a fan base at home.

Take singer Tim Hauser, the onetime Madison Avenue marketing executive who started the first incarnation of The Manhattan Transfer in 1969. That ensemble didn't last long. But when a second lineup began to establish itself with a blend of robust jazz harmonies, pop appeal and, eventually, scores of stylistic inspirations and variations, the world came calling.