Between a Node 2i and DAC: Does Coax cable quality really matter?

Hard to comment on what you might hear.

Yes they make a difference. I’m using a Nordost Silver Shadow which works very well. Most of my system is WyWires so I’m curious how Alex’s Platinum cable compares. Keep looking for a used one to pop up but they don’t.

Yes, you will hear a difference between cables. Nobody can say for sure if there will be an improvement. If you feel an upgrade is in order then audition other digital coax. Order from dealers who offer a trial period. 

I auditioned quite a few S/PDIF cables, also returned a few. Finally I found a cable that significantly improved my digital setup.

+1, fuzztone.
The only way to know by trying couple of cables in your setup. I say this, DH Labs makes very good digital cables. Here are couple of recommendations,

https://www.tweekgeek.com/audiophile-cables/oyaide-db-510.html
https://audioenvy.com/product/home-car-pro-interconnects/digital-coax-3ft/

I can send you the AE Digital Coax for you to try. If interested, PM me your address. 

Changing to a good coax made a big difference for me. Using AP Crystal digital solo. More clarity, better bass.