I hesitate to rule out anything. I learned that when I set out to prove that playing back at 96 kHz didn't make an audible difference anyone could tell reliably. But in the process, I found that
recording at 96 kHz could make a huge difference when working inside the box.
Who knows? My favorite story is when Eric Johnson said some effect sounded better with a particular battery and was laughed at. "Volts are volts, what an idiot ha ha." However...the internal impedance of a battery can vary significantly. If he was using an effect with poor power supply rejection, then using an alkaline or carbon-zinc battery could make an audible difference.
Also, your hearing changes over the course of a day. Your ears are more acute at night because the lack of natural light causes a lower degree of visual stimulus. So if you listened to an X1 project in the morning and an X3 project at night, the X3 one would likely sound better - because it actually would sound better.
We know much less about how the ear/brain combination works than we think...