(...) And for myself: I learned the hard way that once your system is really shining, do not touch it. Even the repositioning of cables can be easily heard in my systems.
I think most of us have such experience. I have been playing with some complete looms of power and signal cables in my system. The space behind the speakers and all the room looked like a cobra lair, several tens of cables were laying around. After getting an extraordinary result and listening for a while, I cleared the space taking out all non used cables and power distributors. After clearance the sound quality decreased significantly. . A good friend who helped me in this session only asked - what did you do to the system?