Over the years I have done several things that improved my system and these are the things that actually really worked;
Anti vibration stand and cones
Acoustic Revive RR-888
Acoustic Revive RCG-24 grounding conditioner
Shorting plugs in my integrated from Acoustic Revive
Lifting the speaker cables off the floor
Separating the RCA interconnects
Last but not least, CPT power cords
I believe all these pieces have lowered the noise floor without having any negative effects. I have A/B over 300 different cable models including 91 power cords. I really enjoy how live my system sounds with zero brightness. The system is very dynamic and the micro detail is right there which allows the emotion of the artist to come through on every song. I have tried removing some of the above pieces but something gets lost when I take even one unit out of the system.
I think there comes a point when a system gets real good and if you do make changes, be careful not to screw it up, that is where I am at. Will I change something over a period of time, sure but not this year.
Cheers,