Not sure what you don't like about what you have? I own C7's being driven by SET 845 tubes. Tried a number of cables - Kubala Sosna, Audience, Cardas, Kimber, Audience, AZ. Finally settled on Auditorum 23 interconnects and speaker cables. Works very well in my system.
I disagree that C7's are not cable sensitive. Perhaps not as much as some brands, but you can certainly change the tonal balance dramatically with speaker cables. Perhaps it has something to do with the quality of the amp driving them?