This two CD set documents American composer James Tenney’s — once described as the New York School’s fifth Beatle — complete music for string quartet and quintet, including his last completed work before his death in 2006, Arbor Vitae. This music is unique, with awesome performances by Quatuor Bozzini, but there are a few points of order to be raised nevertheless. The flimsy cardboard packaging into which the two CDs are stuffed offers no room for proper documentation of the music and, worse still, James Tenney’s name has been printed in such diminutive text on the front cover, it’s easy to overlook that this is a Tenney album at all. These details of presentation matter more with Tenney that for many composers. A work like Koan has a beautiful simplicity in the hearing, but if it’s pointed out that Tenney is using a mathematical process to generate a line that perpetually ascends, an extra layer of understanding is achieved. Arbor Vitae itself and Saxony, written 20 years previously, are sonic monoliths that twist through space motored by infinitesimally small graduations of tuning, changes that are felt more subliminally than actually heard. The set also includes five portrait-like pieces dedicated to Tenney’s mentors and inspirations (Feldman, Xenakis, Ruggles, Varèse, Partch), and the Diaphonic Study for piano and string quartet trades the piano’s equal temperament against subtler tunings in the string quartet: the punchline (and aural illusion) being, it’s the piano that sounds like it is in microtonal nirvana.