These two impressive discs offer an intellectual challenge – not only the seven solo and 1996 Sonata for two pianos (the other player is Ben Smith), but Pace’s giant essay detailing his interpretive relation to the composer. The first item is a seductive start: Invention, with its uncharacteristic repeated notes. Lemma-Icon-Epigram is familiar Ferneyhough “complexity” territory; Opus Contra Naturam is wild, the pianist having to speak while playing.