Maybe it's the influence of Jason Kahn, but I seem to be hearing more improvised percussion discs that deal explicitly with rhythm, notably Jon Mueller's recent "The Whole". Zach has always had this propensity and, on the fine "M.O.S." he unleashes it without reservation. Using a gran cassa, a large, horizontally oriented bass drum, as a resonator along with his tried and true sruti box and drone commander (an electronic device, I take it), he establishes a rapid, consistent tempo, fading in an out of dronier passages. Though the beat is steady, the nature of the percussion used makes the actually sounds cloudier and more indeterminate, providing a really attractive balance between the regular and the hazy. Over 37 minutes, Zach effortlessly maintains interest, deftly varying texture and pitch while keeping the general tenor of things in a sonically juicy area. Very enjoyable.