I don’t mean to be difficult but sound is the same thing as perception of sound. What you perceive to be the sound IS the sound. In other words, the sound you hear is not (rpt not) really completely determined by the enclosed system - the system comprised of speakers and components, room, cabling, the recording and House AC. I know what you’re thinking. And it’s not RFI/EMI or vibration.
What I’m referring to has more to do with placebo effect and expectation bias, yet it’s not psychological than the usual suspects like RFI/EMI or vibration or acoustic anomalies. The listener, even a very experienced and acute listener, can not distinguish between a change in cable or component or the effect of a new tweak, for example, and the effect on the sound by an external force or influence not associated with the closed system of the audio system.
The color of the walls is one such external influence, and one that’s not related to acoustics or vibration. Color of the walls subconsciously or consciously affects our perception of the sound. But that is only one example. The color of magnets is another example of what I’m referring to. For those who experiment with magnets in various locations, try using magnets painted different colors and see how color affects the sound. I.e., RED on aluminum, BLUE on steel, GREEN on glass, any or all colors on wood.