I have two suggestions, Magnan signatures(MS) and Gortz(GO). Both are flat cables and are excellent with all speakers but are an especially synergestic combo with electrostatics. The MS is one of the best speaker cables available and is what I personally use. It's expensive($1000 /8ft pair) but would be my first choice. The GO is a more moderately priced choice but offers a lot for the money especially the copper.
You might want to contact Duke At Audiokinesis who has far more expertise with electrostatic speakers than myself.
You might want to contact Duke At Audiokinesis who has far more expertise with electrostatic speakers than myself.