The Tallis Scholars and Peter Phillips started their incomparable service to the 15th-century composer Josquin des Prez in 1986. And with this, the ninth volume, they conclude their journey magnificently. The “Missa Hercules Dux Ferrariae,” written for Duke Ercole I d’Este of Ferrara, is a work of extraordinary complexity and compositional virtuosity, but its sheer emotional power is remarkable. The Tallis Scholars’ purity of tone, their total identification with the idiom, and their diamond-like articulation are glorious. The “Missa D’ung aultre amer” and “Missa Faisant regretz,” simpler but equally communicative, are also superb. Atmospherically recorded, this is a gem of an album.