These vocal arrangements are much more than the 'background music' another reviewer has described them as - but be warned, they are not the complete Singers Unlimited a capella recordings. What they are are the three a capella albums that the SU recorded for MPS in the 1970s.
The earlier a capella Christmas album is not included. Nor are the four a capella tracks included on the 'Four Of Us' album ('It Could Happen To You', 'Where Is Love', 'Jennifer's Rabbit' & 'Snowfall) or 'Lullaby Of Birdland' from the 'Easy To Love' album.
Once you've heard what is included here you'll probably want what's missing too - just like I did. And once you buy the other albums to get it, you'll probably want all the SU albums, like I did. So you end up buying 'Magic Voices' the truly complete SU recordings (except for the Christmas album).
You might want to consider going straight for 'Magic Voices' to avoid this duplication but that's probably unrealistic if you've only just started listening to them. I hope you enjoy the process of discovery as much as I have.