Your experience with Synergistic Research Foundation SX speaker cables?

@tommylion $749 per 8ft pair retail? Not sure. 
But on a used market, may be. Acoustic Zen Satori or Hologram II, Kimber, Nordost, Cardas, Shunyata? If the performance of Acoustic Zen interconnects in comparison to Foundation is an indicator, I’d not pass up on a opportunity to try AZ speaker cables. 

I have been using the SR30 speaker cables for a while. I just spent some time with the Atmosphere SX Excite cables I demoed from Scott Walker Audio. I was very impressed with the improvements. I’m considering the Foundation as the price point is half, but I’m not sure I can move downstream from the Atmosphere’s. The separation of instruments and the air around them really surprised me compared to the SR30’s. 

if you want something that's even better check out the rectangular OCC single crystal wire made by Neotech, The silver wire is called the Amazon and the copper wire is called the Sahara not cheap though but it'll beat anything on the market OFC at any price, OCC single crystal has been proven to be the best wire for audio for over 50 years now.

I have the Foundation speaker cable (not interconnects) and used them as the prime for well over a year. Still have them, put away. Try the QED Supremus. They cost a bit more but are roughly in the same price ballpark.