EVERY connection seems to be as important as the next.
Forgive me if I am preaching to the choir, but I just had a significant improvement in my system that was most surprising. Many moons ago the wall wart power supply to my subwoofer crossover cracked. Eventually, the crack grew worse and it made one of the blades loose. today I literally bandaid fixed the wall wart by tightly wrapping the cracks on the casing with a couple rounds of electrical tape, thus squeezing the loose blade nice and tight again, thus reducing the micro-vibrations. Well, I wasn't expecting much, and really just did it for the safety of it, but I am happy to say, that the improvement is not subtle at all. The ENTIRE Frequency spectrum became clearer and the image tightened up considerably. Makes sense as the wall wart is basically the bread and butter and power cable of the crossover. Wth the loose blade, It was making the whole system sound fuzzy by comparison. I expected maybe some tighter bass , but not a top to bottom improvement. I even hear a lower noise floor! Could also be that the wall wart with its loose blade, being plugged into the same duplex receptacle on my conditioner as as my preamp, was contaminating the whole outlet. A very welcomed surprise indeed, and a real eye opening experience.