What to add next? I just bought the Cary to replace a NAD 515 carousel and was a bit disappointed in that the change didn't overwhelm me. I am thinking of changing the interconnect, but to what? Listen to mostly jazz, classical and opera.
As to Gunbei suggestion I completely agree and want just to point out a simple philosophy on that case: your NAD was successfully hiding downsides of your NAD carousel and now it's unsuccessfully revealing the strengths of your Cary CD player. That means that if you trade your AudioQuest Vipers for RadioShack wires and get VTL IT85 or Pathos for example you'll definitely benefit much more. You can also research Unison Unico integrated hybrid amplifier and order it for the audition almost free+shipping.
are you willing to get an interconnect that is half-price of your CD-player?? i think you should look somewhere else. if you do not like the performance of cd-300 you should give it back to dealer or simply sell it and change it. tastes are all different and there is no wonder to it.