This album is not about “plunderphonics,” but you’ll find a lot of the sound morphing that has become characteristic of John Oswald’s work. And without the “who-did-he-mistreat-this-time” hook, Aparanthesi stands as Oswald’s most difficult, challenging album yet. It has a lot to offer though and every listen reveals new details — and there are enough in here to last through many listens. The album presents two versions of Aparanthesi, a 30-minute piece built on a single note: A. A piano is at the center of the piece, but it is joined by sine waves, field recordings, strings, and a piano tuner. But everything that happens has been filtered in order to “retune” it to A or one of its harmonics. You can compare it to looking at the world through a lens that would make all light converge toward a tiny point. And yet the experience is much stranger than that, especially since Oswald operates slow morphs between the most unrelated sounds. The two Aparenthesi, studio and concert versions, differ significantly from each other — enough to justify the release of both pieces. The dynamic range is extreme, some sound events happening on the threshold of audibility, and yet both pieces begin with an overwhelming chord (for the concert premiere the audience was asked to wait outside the concert hall while the chord was sounded inside, otherwise it would have been unsafe) that slowly descends toward nothingness. The liner notes consist of another conversation with the fake interviewer Norman Igma in which Oswald takes both tracks completely apart, explaining every little detail as if he was determined to dispel every iota of mystery in the work. Well he fails miserably: even after this difficult read, Aparanthesi stands as one of his most enigmatic works, worth every bit of effort required from the listener, and that despite is rather anti-climactic nature.