Suggestions for Giant Killer rca coax digital cable under $500 used

WOW!! What a request.

The idea the Cable will be one that is not experienced prior to purchase/parting with monies and as a used item will most likely be a non-returnable goods.

If it helps in any way, the Wire Type D.U.C.C used in a Cable, proved to be very attractive between a CDT >DAC

Townshend F-1 Fractal Digital cable is as good or better than all these expensive cables. 

Analysis Plus Digital Oval.

I use a Wireworld Starlight Gold, which I believe is silver and it sounds very nicely balanced. I know swapping cables can be fun, but if you’re looking for “giant killer” results, I think you should upgrade your dac. If you sell the Pontus and move up to the Venus, you’ll likely end up spending very close to what you would fooling around with cables.  Cables are important, but the box is more important. 

Came across these guys recently.  Haven't tried them yet ... thought I'd pass along...