What is the most important cable in your system

I have a system that has evolved quite a bit over past 7 years with a variety of amps and speakers, in and out of the system.  My dac, streamer, server and power distribution have all stayed the same.  

And while I’ve noticed subtle changes as I swapped out and upgraded all of my Ethernet, XLR and speaker cables, the biggest difference I have found has been power cables.  Most recently, upgrading from the Audioquest Firebird HC to a Dragon HC on my integrated amp has produced the most profound improvement I’ve ever experienced from a single change.  And that includes both cable and equipment changes.  It’s like a different amp.  

Must be synergy, but I never expected my system to improve in so many ways without any downsides…and I say this with equal conviction today as the day after I first introduced the Dragon HC to my system, and that was about a month ago.

As always, YMMV but I’m still stunned by the improvement.

I was thinking about my system and the changes I described and I now realize I forgot to include another change that happened at the same time that I completely discounted that could have been part of the improvement I realized…

When I took out the Firebird HC from my amp and put in the Dragon HC, I then, at the same time, replaced a Hurricane I had on my streamer with that Firebird HC that was on my amp.   I’d always been told that the power cables to components that were 100% digital didn’t matter that much.  

However, now in hindsight, I realize and have to admit, that some of the improvement I gained may not just have been from the introduction of the Dragon HC but also the removal of the Hurricane.  I may do a ‘control’ test and put back in the Hurricane on my streamer and see if my gains go away but I’m loving the sound so much right now, that curiosity isn’t greater than my current enjoyment.