I agree with the Cary CD 303 recommendation. Owned one and it convinced me that HDCDs, despite some opinions to the contrary, are generally superior in sound quality. I highly, highly recommend the Rachmaninoff "Symphonic Dances" by Minnesota/Oue issued by Reference Recordings. Fantastic piece, fantastic performance, fantastic recording. My wife really likes the Dixie Chicks, and their first album was HDCD encoded (don't know about the rest), although not as noticeable a difference as with the Reference Recordings catalogue.
Hope that helps!
Hope that helps!