As @stilljim stated, some of the early US CDs were incorrectly mastered using the RIAA equalization for vinyl records. These CDs were pressed and sold by retailers. I believe these discs were recalled, but in any event, this hurt the public's experience with the new format.
These albums were then mastered and released using the proper EQ for the digital standard.
These albums were then mastered and released using the proper EQ for the digital standard.