EMI testing requires a Faraday cage. The video with the FFT analyzer testing the effectiveness of a PC on an amp is fun to watch but keep in mind that this is a comparative test. Like when we listen to a stereo component, we compare it to something else we have heard- be it live music or another component. That is a subjective evaluation. What this guy in the video is doing is also a subjective evaluation but with an analyzer. Just because he has a computer outputting numbers does not make his comparison less subjective than someone doing a listening test. Many people with highly developed listening skills can match or outperform measurement equipment. Especially because we don’t always know what to measure or how to measure it. The guy in the video could do the same tests again on a different day and get different results depending on the state of his power grid and local interference in his area.
An objective test must start with a baseline that is calibrated and repeatable. That is why EMI testing requires a Faraday cage. That is the EMI equivalent of an anechoic chamber. That way even his test equipment is isolated from outside influence.
I’m not knocking comparative testing. We often have no choice and comparative listening is how we make purchasing decisions. Item A sounds better to us than Item B and so we are satisfied with our purchasing decision until we hear something better.
I heard a difference in different PC’s and I hear a difference with and without one. That is how I made my purchasing decision. If I can’t trust my ears who can I trust?