Best cables for Simaudio Moon system??

Perhaps you could also try Nirvana and Purist cables. I never liked Cardas, it is non-linear with enough distortion, usually bass heavy,slow, thick, doesn't get tremble right etc. It is audiophile tone controls and not a good one.
Manufacturers of equipment rarely if ever find the best cables for their stuff, don't listen to them.

I'm now getting great results with Cardas Clear throughout my entire system. The Clears are very neutral cables across the frequency spectrum, unlike previous Cardas cables (as Inna mentioned above). For the money, they offer greeat value compared against much more expensive high end cables like Transparent, Synergistic and MIT.

I was recently at the Toronto Audio Video Entertainment Show and a lot of Simaudio demonstrations were pairing Moon equipment with Nordost cables. I've never thought Nordost was my cup of tea, however the new line of Nordost cables (especially the higher up the line models) sounded fantastic with the Moon equipment.

I will second the NORDOST suggestion (from personal experience with my speakers)

Before you make your final decision, you may first find out just what does THIEL showcase their kit with.
Does this factor also matter in achieving "best" synergies? You betcha, especially with high-end gear.