As it slides towards it forty-fifth anniversary, ROVA (AKA the ROVA Saxophone Quartet) shows no signs of easing up, let alone slowing down, on latest album The Circumference of Reason. Saxists Bruce Ackley (soprano, tenor), Steve Adams (alto, sopranino), Larry Ochs (tenor) and Jon Raskin (baritone) navigate the murky territory between avant-garde composition and free improvisation as well as anyone, bringing in a composerly gravitas and a playful whimsy at the same time. Composed by Adams, “Xenophobia,” “The Enumeration (for Glenn Spearman)” and the title cut reach deep into the players’ quintessence, adding fiendish asides and emotional outbursts to otherwise serene settings. “NC17,” an improvisation devised through a set of cues given during performance, appears twice, with enough difference between the tracks to earn the “Version 1” and “Version 2” subtitles. Besides “The Enumeration,” the band also pays tribute to Glenn Spearman with the late saxophonist’s bluesy “The Extrapolation of the Inevitable,” the most accessible piece here. In the spirit of the Art Ensemble of Chicago and fellow all-sax ensemble the World Saxophone Quartet, ROVA puts in the effort for some serious playtime.