A welcome reissue
I'm glad to see this disc (originally from 1994) reissued. It is an interesting take on one of the best-known pieces in the repertoire, and it's good to have some more of Allegri's work available – even if it isn't terrifically inspiring.
The principal interest here is in the two versions of Gregorio Allegri's famous setting of the 51st Psalm, known as "Miserere". The first is quite a revelation, with Baroque ornamentation rather than the more familiar version with the stratospheric treble/soprano notes which probably date from the Sistine Chapel's original ornamentation practice. It's rather lovely, even if it is a bit of a shock to the system. A Sei Voci also sing the more familiar version to close the disc. They take both very slowly compared with other modern recordings like The Tallis Scholars and the Sixteen which can feel a little funereal at times, but they're well sung.
The rest of the music is a mass setting and three motets, also by Allegri, which – to me anyway – aren't all that interesting. They're perfectly decent works, but compared to many of the wonderful music by famous composers like Josquin, Byrd or Palestrina, or the fabulous stuff by obscure composers unearthed more recently by ensembles like Cinquecento and The Brabant Ensemble, it seems pretty uninspiring. It is redeemed a good deal by the performances, though. I haven't always got on with A Sei Voci's performances in the past (their Josquin recordings in particular) but here they sing beautifully, with a lovely, richly textured sound and genuine engagement with the text.
I certainly wouldn't recommend this as the best recording of Allegri's Miserere (for me, that's still The Tallis Scholars' 1980 recording) but it's a very interesting disc which I can recommend.