If you take Krall out of the topic, you can place anyone in. It may not be a matter of the artist being so good, rather the artist sounds good! Some types of music can bring out great qualities in recordings. And, secondly some recording engineers and studios spend quality time getting a great recording. On a quality HiFi system, one can really hear this.
I happen to think DK is a very talented singer and some of her records are quality recordings. But one can find great pop, rock, punk, blues or other genre recordings as well.