Amazon.comThe title says "Mass for four voices" and that's exactly what these performers give us: four voices, one to a part, with a female soprano and a male alto. There's always a tradeoff when you do this sort of thing. With a larger ensemble you can gain tonal richness, blend, and sustaining power over long phrases. With a small group of four voices, you gain flexibility and clarity of line, which in this case is quite striking. But sometimes this kind of clarity is too much--the intricately woven polyphonic fabric can fray more easily, as it occasionally does here. But there's no question as to the virtuosity of the individual singers, all of whom are veteran early music performers, both as soloists and with various ensembles. It's not surprising, then, that what stands out on this program--which includes short pieces by Taverner, Tallis, Edwards, and Sheppard--is the stylish, sensitive ensemble singing. --David Vernier