Today, I'm going with the vocal setting of "O Domine Jesu Christe" from Francisco Guerrero's "Sacrae Cantiones." (Also, playlist.)
Provided to YouTube by The Orchard Enterprises Sacrae Cantiones - O Domine Jesu Christe Ii (A 4) · Jordi Savall · Jordi Savall Francisco Guerrero: Sacrae Cantiones ℗ 2009 Alia Vox Released on: 2009-08-25 Composer: Francisco Guerrero Auto-generated by YouTube.
Attribution(s): "Glockenspiel Bells" by cocoparisienne (via the Visualhunt site).