Where do you stop?

I bought some 99.9 % pure silver speaker cables. I read the reviews before investing in them and they talked about how they seem brighter and most felt it was because of the lack of noise and more imagining. Some didn't care for the new sound but most loved what it did. I really liked the change so much I bought some to go from my preamp to my mono block tube amps. That sounded even better. So what the heck I bought more to use from a phono amp to my pre amp and then some silver phono cables. Every time I added them into my system it sounded better and better. So here is my question, The Silver in the cables according to the reviews are superior because they conduct electricity better than copper and have a lower impedance if my memory serves me correctly. What happens to the signal when it meets copper wiring in speakers or other gear? Should all the wire be replaced anywhere it can be and will it continue to sound better?