Puppet, I've owned the 560's for years, and after about a year, I changed the stock 22ga (or 24ga) wire to 16ga Accoustic Research cabling, and noticed an opening up of what little highs there were, and an increase in percieved detail that was not subtle, as well as a reduction in noise that was nothing short of drastic.
The stock cabling is very, very cheap.
I'd suggest you go to home depot, and pick up whatever length you need of 16 or 18ga lamp cord. It's cheap, it's quite good (some audiophiles swear that there's no audible difference between 12ga lamp cord and the most expensive Cardas or Virtual Dynamic cables. I don't agree, but I think lamp cord is still quite good). Then just cut it to length and strip the ends.
And a note to all those bashing you:
No, the Z-560's are not the pinnacle of excellence in sound reproduction, in fact, they're quite bad on the grand scale of things. They're not Wilson Audio or Martin Logan, but they are cheap. In fact, they're REALLY cheap. They're the best in their price range at some things (big bass, overall volume) and not so far off in others that it's laughable (fidelity, clarity, flatness). There are more musical speakers out there for the price, but not for a basshead.
The 560's are the Sony V6 of the desktop speaker world. They're better than most people will ever own, they're boomy, loud, and cheap, but they're a DARN good value for a lot of people.
If someone came in asking for advice on making his V6's better, you wouldn't tell him that he owned absolute crap and that anything below an Omega2 setup is laughable, you'd either help or shut up. I think that it shows a lack of class not to afford the same respect to puppet and his question.