These things did not work FOR ME:
- Green pens for CDs.
- Rings that went around the circumference of the CD.
- Noise filter on the Ethernet line.
- Fancy power cords.
- Fancy interconnects.
- Fancy USB cables (these days -- they helped back in 1990 or so).
- Raising speaker cables off the floor with insulators.
- A reclocker was effective with one equipment combination, but deleterious with another.
- A friend put crystals on my power cords to show me what they could do (I’m not kidding!). They didn’t do anything I could hear.
- Ferrite cores on speaker cables and power cords (though they might be helpful in a high-RF environment)