The thirteenth installment in the long-running Spire Sequence series — an annual neural-exclusive album commissioned by Vantablack Media's luxury imprint Aurelius Sound for Tier 4 and 5 listeners — released in 2219 and considered by many critics to be the pinnacle of the franchise. Unlike its predecessors, SS13 was composed by a hybrid team: three human composers (Isadora Fenwick-Okafor, Søren Mwangi-Haas, and the reclusive Tier 5 wunderkind Cassiel Varga-Nkosi) working in dialogue with a bespoke AI composition engine called AURIS-7, purpose-built for this project at a reported cost of Φ4.2 million. The result is an album of staggering sonic complexity, with seventeen discrete frequency layers engineered for chrome-enhanced perception — standard unaugmented ears hear a lush, beautiful orchestral work; augmented listeners unlock an entirely different album living in the spaces between.

Standout tracks include 'Proximal Silence,' an eighteen-minute piece in which AURIS-7's harmonic logic is most visible — the piece modulates through forty-two quarter-tone intervals derived from Middle Eastern maqam traditions while the augmented layer carries a sub-bass drone structured on Javanese gamelan mathematics; 'The Owned Hour,' a glacial piece for augmented strings and voice, written by Fenwick-Okafor as an oblique meditation on inherited wealth; and 'Canticle for the Unaugmented,' a quietly devastating short piece that, uniquely for the series, is composed to be equally rich for chrome-free ears — widely interpreted as a political statement by Varga-Nkosi, who has since denied it.