Chamber Jazz is a genre of jazz that developed out of Cool Jazz sometime in the late fifties early sixties. Related to West Coast Jazz as many players were by then settled in Los Angeles. Small acoustic based ensembles with some classical forms incorporated. Instrumentation was also eclectic with violin, oboe, sometimes tabla which led to early form of World Music or later in time New Age music.
These collections I find good for cocktail hour or dinner time. Just instrumentals.
Proponents of this style were Chico Hamilton, Paul Horn, Jimmy Giuffre, Buddy Collette, Jim Hall, Dave Brubeck and the Modern Jazz Quartet among many, many others.