Are you using the balanced or single ended outputs? What amp(s) are you using? Speakers, headphones, or both?
[Edit] ah - I see from your sig that you have a ppx3 and hd600's, so youi are talking single ended. [/Edit]
fwiw, I have a 588, and use Monster 850i for balanced connection to a Stax 007t tube amp for Omega II's with good results.
For single ended to my speaker setup or other headamps, I use Luminous Audio
Synchresta Reference IC's. There are many others as good, and I am of the school that avoids most of the techno jargon around cables, and the claims of astounding difference in performance. I do firmly believe that a high level of materials, design, and build quality is important, and am willing to shell out $$ for that, rather than the overly touted sonic benefits.
I have also use IC's from Dan Kaps at
Heartland Cables, and highly recommend them as hugh value for the $$, particularly when fitted with Eichmann Bullets.