Why some CDs sound bad with a DAC?

Hi Everyone,
I recently installed a Birdland Audio Odeon-Ag 24/192K upsampling DAC with a re-clocker. For the most part I have been blown away by this product. It does magnificent things to 99% of my CDs.
A couple of them, however, are sounding much WORSE through the DAC!? Why might that be? Yesterday, my CD jukebox pulled up "Prince Caspian" from the CD "Billy Breathes" by Phish. The sound was all distorted and harsh. One or two other tracks have reacted in a similar way. Any thoughts, suggestions, advice???

Thanks in advance.

Tom