This is a fantastic production by Naxos, a Gregorian chant-specialised Italian choir that will blown you away. For once, the best singing is NOT accomplished by monks - with maybe the glorious exception of Fontgombault - but by professional singers.
This is not a surprise because the best recordings I can recall are those well-known, made for Philips by the schola of the Hofburgkapelle, Vienna under Hubert Dopf S. I.
(recordings that are luckily still accessible, now through an American company)
In short, one of those few records edited by Naxos that deserves a place in your library!