Which systems do sound different and which don’t?
All systems sound different. Room, component tolerances and age, humidity, temperature, pressure, YOU all conspire to alter the sound.
Why is that?
Do the math.
What parameter of the system make the difference?
"Some of my work involved tuning the power supply. It may come as a surprise to learn that you can change tonality without even touching the signal path, because the signal originates from the power supply.
The impedance curve of the N11’s power supply is absolutely homogenous from DC to 200kHz, which creates a very balanced sound. I also tuned the resistors for the voltage gain, using a mix of carbon and metal resistors to create a neutral balance. There are a lot of preamps that claim to be ’neutral’ or ’in balance,’ but there are different shades of ’neutral.’ If you have a tube preamp, for example, ’neutral’ is at a different level than solid-state; it’s not better or worse, but it is different. It took a lot of work to find the tonal balance I like a lot that measures well, with low noise, and fits very well in the Noble Line." [emphasis added]
The truth is that you don’t know.
I don’t think you read what I or Mr Galeis wrote. If you did, it’s beyond your ken.