Tweaks/Components supposed to enhance your sound - but did not

What did you add to your HiFi system expecting a sound improvement, that didn't work?
I can't tell there was a clear improvement after adding the following:
- a record weight to my vinyl listening sessions;
- speaker cables from a famous brand in replacement of my DIY speaker cables;
- "black discus" from Mad Scientist (I have them attached to speaker cables);
- a dedicated power conditioner/ distributer.

Maybe it's my ears, maybe the actual circumstances (lack of time, a baby in the room all the time...), but I can't hear any sound improvement.
Did you add anything that didn't bring any change to your sound?
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My response is two fold, so l hardly noticed improvements with tweaks until l upgraded my main components, especially my amp, and then applied simple and relatively inexpensive tweaks to my power delivery system. Now, mostly anything I change out, I hear. However, power is a real issue, IMO, and that varies with where you live, so somewhat out of your control. After, moving my same system from one home to another, l was really rewarded by just being lucky.

What I've found to be very interesting, in my experience, is that my old cables and interconnects, which I consider to be average, did not prevent me from hearing the profound changes to the sound of my system, after I upgraded my components and power. I'm not saying that cables don't matter, so I'm looking forward to replacing them. I'm just saying, that the component and power changes now allowed me to hear those cables, and in my case, this was a leap in sound for me anyway. So, I am excited about tweaking out my system now that I can easily hear these differences.