HOW LONG has this been going on? Right under our noses, it appears, we've had a polished cabaret quartet, a jazz vocal group called Mad Romance.

Comparisons could be made, but judging from their near-perfect vinyl debut, Mad Romance doesn't need them -- they're not studio-slick like Manhattan Transfer; not cloying and cute like Montgomery, Plant & Stritch. The Washington group offers unadorned, exuberant, exhilarating harmony singing.

The (sophisticated) fun begins with an energetic "Taking a Chance On Love." "How Are Things In Gloccamorra?" from "Finian's Rainbow" seems an odd choice, but given a subdued and elegant treatment, it turns out to be one of the record's highlights. "I Get A Kick Out Of You" gets a novel rhythmic reworking, and the group borrows a tricky vocal intro from Stevie Wonder for Dave Frishberg's funny "Blizzard of Lies." Only "Over The Rainbow" and "My Favorite Things" seem out of place here, and that's because not much is done to justify these predictable choices.

Rick Harris supplied the crisp production and witty vocal arrangements, and he, Pam Bricker, Holli Ross and Eddie Vann execute them with verve, though the singing sounds a bit over-cautious at times -- they could stand to swing a bit more. Mad Romance is backed by a trio led by pianist Louis Scherr, which provides support while standing out of the way of the flying vocal lines. MAD ROMANCE -- "Mad Romance" (Zanzibar Records ZBR-101). Appearing Sunday at Lenny's.