Your post represents what I love and hate about the internet. I love it because your question is clearly communicated and others with relevant experience donate their time and expertise to answer your question. The negative is that you are the one with all of the equipment, including your ears, to answer the question that you pose. To rephrase your post…. I trust the ears of others that I don’t know, more than I trust my own ears, so tell me what to do. My power amps are plugged into a very expensive conditioner. I also have a whole house surge protector. I live in an area with frequent lightening storms, so the isolation is important. My suggestion to you is to decide how important surge protection is to you and then trust your ears more than people that you don’t know. Try answering your own question by listening. If you can’t tell the difference, then great. Go with the added surge protection.
I love the “edit” function, because one other thing entered my thoughts. Maybe, your question wasn’t stated clearly. Maybe, you are stating that with a short A/B you could not hear a difference, but you would like to try a longer comparison and wanted suggestions as to what to listen for and perhaps, what to use as source material…ie….music.