Any experience with Signal Cable for REL sub?

Yes, I have Signal Cable. Works fine. I can't tell how big an improvement it made as I purchased it for my Stadium 11 which didn't come with a cable. My Stadium 111 which I bought later came with a standard cable but I never had a listening panel to compare them. Trying to change the cable while running back and forth trying to listen did not seem likely to tell you much. I eventually replaced the stock cable on the 3 with one made by an individual that advertises on Audiogon. Happy with that one also. As I run both at once any comparisons involve rebalancing my system so I haven't done it but my impression is that either is a definite step up from the standard cable.

I get feedback on my Rel from the high level inputs when everything is off, I can just hear slight hum. I have mono block amps, and had some problems with the setup. Anyone else have those problems? Could another cable, the Signal or Audioquest make a difference??

I upgraded my REL Strata III cable to the Signal Cable and I'm satisfied with the improvement it provided. The bass tightened up and seems more defined. The cable is very well made with nice spades on the amp side that makes for an easier connection to my McIntosh MC275.

For years I have wondered how upgrading the stock Rel for my B3 to anything else would make much of a difference and just 3 weeks ago I got my answer. I bought a Nordost baseline sub cable with the neurtrik and spades for a high level input. All I can say is the amount of information I hear is tremendous. All low notes sound so much more natural. I think because of the speed silver brings, the time alignment together is so much better. I had no idea what I was missing (neither could my dealer).

Sorry I can't comment on Signal Cable but I would think any upgraded cable should be an improvement.

Where did you find the Neurtrik Nordost? I don't see that anywhere on the web.