In the hobby of Hifi audio, the rabbit hole goes endlessly on power cords, power conditioners, XLRs, RCA, digital, and then there is the other endless money pit doodads in tweaks. My Eureka moment was when I bought a Shunyata Sigma V2 power cord for my Niagara power conditioner. Like the conditioner itself, the power cord into the wall outlet just makes everything just sound better, and in a meaningful way.
My favorite tweak are Symposium's Rollerblocks and platforms. Perhaps it shouldn't be head-scratching, but it sure seems a bit snake-oil-ish from a distance until you pop a few of those little devils below your front end components. I was pleased with the - bringing things into focus - affect. It just makes the good stuff you have, a bit better. It's like sprinkling a bit of salt & pepper onto the cream cheese that's spread on a bagel, it just gives it more pop in flavor, hah!