The Dale Warland annual Christmas concert is an event that compels people from neighboring states to make the trek, usually through cold and heavy snow, to St. Paul. If I had any idea of their concert schedule at all, I would seriously consider flying up from where I live, practically at the opposite end of the country, in Louisiana. And, yes, they're that good. Fortunately, they record. First, to some extent, it's a matter of doing the basics perfectly.
Pitch is dead-on, as is rhythm, and their diction is clear.
Often the latter two go hand in hand. When everyone attacks and releases together, consonants sound together and usually more sharply. Although the CD thoughtfully provides printed lyrics, you don't really need them. Yet, in the matter of pitch, I would add that their concept of intonation differs from most other groups. That is, Bb seemed always the same pitch, regardless of the key.