Shunyata comparison

New noise filtering and eliminating the complications for digital, analog and HC specifications. Not really an Upgrade from HC to NR, unless move up to Sigma NR 

I have both cables that you mentioned. The Alpha HC to me is a warmer sounding cable. The NR is more neutral. Even though the Alpha HC is noted to be for High Current, I do use it on ALL components even low current devices with success. SO in summary its not which is better, its do you want some warmth or you want some neutrality?

here are the salient characteristics of Sigma NR in my system. It does not add warmth but does add otherworldly bass impact and fullness. It shimmers on top and is transparent. Perfect for a system lacking excitement and refinement. The only negative is that although very musical it won’t take the edge off poor recordings but it will give them a little more life.
In direct comparison the aq hurricane is ‘warm’ in comparison and a little darker which might be perfect for others. this is in my system and ymmv. both are very good cables.
oh one last thing. the flexibility of the Sigma is a plus and my conclusions are based on using them on my amp. Difference would be apparent to anyone w ears

I use the Sigma NR on my digital source and Alpha HC/Alpha NR on my Amp. I find this to be best configuration for my system and listening tastes. I am beginning to think that having ONE Sigma NR placed strategically is all you need, otherwise it could be too much of a good thing. I also find the Sigma to have a closer to the Front row sound and a incredibly expansive soundstage compared to the Alpha’s. Great cable and would like to hear a second Sigma to conclude my theory. ;)

I also have a King Cobra V1 "i" which is very warm, laidback and a perfect antidote for poor recordings.