Colin Stetson/Mats Gustafsson

Free-improvisation, by its very nature, is music at its most dangerous. Even with great musicians there's no "sure thing." It can fail so easily — being static, boring and self-indulgent — that successful collaborations seem magical simply because they work, in spite of the odds. Stones features two saxophonist/improvisers with peerless credentials and yet, while they have tons of technique and experience between them, much of the four-track, 35-minute album is aimless, with little clear direction, form and identity. Where having two distinct voices would seemingly be a natural approach, they opt for a sameness of sound shapes, registers, dynamics and motifs. There's a great deal of squonk, but little eloquence. Stetson and Gustafsson are content to produce momentary confluences, rather than challenge one another to break through their habits of expression. This isn't to say there aren't instances of genuine creative interplay, far from it — moments of intensity, nuance, genuine communion and emotional depth are found throughout. But they are scarcer than we rightfully expect from musicians of their stature.