Ditto to the above. DDD just mean all Digital. The first D is for Digital Recorded, 2nd D for Digital Mix, and 3rd D is for the final format on the CD. "A" is analog and includes all pre-digital recording put on CD and some artists who still record using analog equipment. If you see AAD for a CD reissue of a recording that was once on a record, it means the original master was just put directly on a CD. If you see ADD, it means the recording was digitally re-mixed before it was put on the CD. For classical music I really like the AAD or ADD better than DDD. There are some recent 1990s EMI recordings that are ADD.
