I should have expected some kind of new perversity from this very unpredictable ensemble when I noticed that the cover picture on this CD of the Mass of the Blessed Virgin is a portrait of Lucrezia Borgia!
A Sei Voci can sing. They sing extremely well on their recording of the Miserere and a mass by Gregorio Allegri. Thus it's mere perversity that they choose to sing these motets and mass movements as an imitation of the Mormon Tabernacle Choir, conducted by Herbert von Karajan. When singing Josquin-era polyphony, more voices are always less, and Sei Voci in this performance is really Undici Voci - eleven voices, without the tight ensemble tuning and dictiom to make such a choral onslaught attractive. Thus there is NO sense of independence in the four<five lines of the mass. The prolations (changes of count from two to three and back) are mushy. The whole chorus swells and fades together with no sense of the movement toward cadences, there are truly illogical moments of rubato, and the tempi are sluggish; that's the "von Karajan" effect.
The acoustic mushiness of this performance is aggravated, I suspect, by the choice of recording it in the sanctuary of the Abbey Fontevraud. I've performed there myself. It's a stunningly beautiful and tranquil place for music , but the acoustic is not supportive of polyphony, with echoing resonances of 3, 7, and 8 seconds. On the CD, this is heard as white noise. However, on your next vacation in France, by all means include Fontevraud, even if there is a concert scheduled. Google it, and you'll see why.