Your experience with Synergistic Research Foundation SX speaker cables?

I'm a fan of SR's stuff. I use their Element series speaker cables, which also use the tuning bullets.  I haven't heard their Foundation series, but have heard good things about them. If you like them, go for it. SR is pretty receptive to questions, so I'd reach out to them directly if you have any. They want you to be happy, not necessarily to up-sell you a product you don't need. JM2CW.

I tried the SR Foundation XLRs and power cable as loaners from The Cable Co. lending library. At the time I had Acoustic Zen Matrix Ref II and Absolute Copper interconnects and Acoustic Zen Gargantua power cords. The SR power cord was an improvement in detail and speed but it wasn’t as refined overall. The XLRs didn’t match up to AZ they were slightly grainy and less natural sounding. I never tried the SR Foundation speaker cables. 
Now whatever I heard in my system with my ears doesn’t at all translate into what you will observe with these cables in your set up. Give it a try. But I think going up to next level SR Atmosphere may be a better choice. 

The cables I have been using are old TARA Labs Prism Nexa. The Foundations are quite a step up from those, as they should be. I really like what I’m hearing from them so far, and the price seems reasonable for what I’m getting. However, I haven’t explored speaker cables for years, so have no experience with current, similarly priced, competitors to the Foundations as a reference. Is there anything out there at the same price that will significantly better them?

@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.