An experiment, to celebrate the Monteverdi Choir’s 50th birthday season: Three works by composers born in 1685—Handel’s “Dixit Dominus”; Scarlatti’s “Stabat Mater”; Bach’s “Mein Herze Schwimmt in Blut”—were performed at London’s Milton Court on Sept. 25. The aim was to release live downloads on Sept. 26. Soli Deo Gloria missed its own deadline by a few hours, but never mind. Rough edges are minimal, and the performances fizz with John Eliot Gardiner’s dramatic sense. His choir, from which the soloists are taken, remains matchless.