Let me give you an example that anyone can try: When I first watched the 3-D version of the movie "Gravity" using my Oppo Blu-Ray player, I didn't have the iPurifier in the system, so jitter was higher. I totally missed some of the context of the movie because this is laid-out in the first minute of the movie, with radio chatter between earth and the space shuttle. I could not make out what they were saying in this chatter. It's mostly high-frequency sound.
After adding the iPurifier, I watched the movie again. This chatter was now intelligible and I understood the dialogue immediately, even though this is at very low level. The movie finally made sense to me.
This is very natural part of how our brain works. When you swapped in the iPurifier you were focusing on its effect which in turn would cause your brain to focus more on details. This is the same as someone reporting that after they made some change all of a sudden heard an instrument they did not before. The sound was always there but they did not pay attention to it.
Our hearing system is delivering megabytes of information per second to our brain. Much of this information is thrown away out of necessity. The moment you enter comparison mode of audio gear, the brain changes function and is able to focus more and find new things that were always there but discarded.
Since you brought up video, broadcast monitors have a black and white switch. Push that button and color is gone. It is used all the time to let someone see errors in luminance (black and white) would can be obscured by the prettiness of color. Nothing is changed in video signal when we do that but it aids the brain to better find what we are looking for.
This issue by far the most important way audiophiles go wrong. They swap gear, focus more, head more detail and declare the new gear must be there. In reality nothing is changed but their mindset. This is why blind tests work so well: they take away the knowledge of whether something has or has not changed. That equalizes the playing field with respect to how you brain analyzes sound. The fact that blind tests don't agree with sighted ones, proves this aspect of brain function.