Among the ways to pin down Kneebody, a resolutely unpin-downable band, a few come rooted in plain fact. The group uses a common jazz instrumentation trumpet, saxophone, rhythm section to make a somewhat less common amalgam of urban-signifying genres, from electro-pop to punk-rock to hip-hop. Four of its five members met in the late 1990s at the Eastman School of Music. Its most recent album, Twelve Songs by Charles Ives (Winter & Winter), featuring the vocalist Theo Bleckmann, was nominated for a Grammy this year, in the category of best classical crossover album.
The applicable word there is crossover, which Kneebody has claimed as a directive, more for aesthetic than commercial reasons. This week, during a four-night run in a black box at the Theaters at 45 Bleecker, the band is playing two shows nightly, with featured guests including Mr. Bleckmann and the indie-rapper Busdriver. (Only one of them will be singing Ives.) The run began on Wednesday with the trombonist Josh Roseman and the guitarist Ben Monder: jazz musicians both, though that was only a common dialect.