Has anyone heard the Joule Electra Stargates?

Findoc, I would just call or write to Jud and ask him. I believe that the Joule/Merlin tandem, which have been shown together for years, included Cardas. I may be wrong, but I think Merlins are wired internally with Cardas, so that would make sense. But that logic doesn't necessarily apply to your Sonatas. I chatted with Jud when I sent him my LA-100mkIII to be upgraded and found him to be very approachable.

You might also ask Silverline what they recommend. Many speaker manufactures use specific cables when they "voice" their speakers.

I think Merlin recommended the Cardas Golden Cross or Golden Reference because of the internal wiring, but it also helped to flesh out the low end on the older VSM-SE design. The VSM-M design does that on it's own, so the "M" version would probably sound good with the Neutral Reference or something less "warm". As always...it depends on all of your other eqipment. I don't think there's any reason you need to use Cardas for Joule amps.

I have the Stargates on my Soliloquy 6.5s (92db and 8 ohms). Amazing combo. These amps have cojones. Easily bested my MF A3CR solid state amp, and my Manley Stingray. Bass that sounds like they have 300 watts, not the 30 watts they actually have. SET midrange magic. I am quite happy with these. Should work well with the similar Silverlines.