When to Tweak is the Question. Remove every tweak you have done and listen. Then starting with the source start over one at a time. Listen to each tweak reinserted.
Start with the power cords first. When all gear has the upgraded PC give it a serious listen. Then add footers starting again with front end. Then add any other tweaks like weights, plinth material,cable lifters,
You may learn that a tweak or two was unwarranted or dead on. Have fun and learn more about your system. have fun.
charles