For Your Edification and Enjoyment re "Burn In", etc.

bluemoodriver, while not an authority, I do not believe the presumption that flooding a room with two channels with opposing polarity will result in cancellation. Audiophiles have many times mistakenly played speakers that have one channel out of phase, and the result is not cancellation. I do not see how switching to mono will cause the sound to disappear, cancelling as with matter/antimatter. 

Perhaps my understanding is not nuanced, but I suspect this test will not do what is suggested. Those more knowledgeable than me may disagree and instruct.  

bobinwi,

You can call it science or psychoacoustics the truth is that there is very little in terms of scientific proof to support either side. The problems with blind tests are well known as are the manufacturers that make wild claims. Listen, decide for yourself and dont listen to any of the "experts". All of the inclinations conscience or not are just as present among the experts as they are among the hobbyist. But once you voice your opinion as an expert it is doubly difficult to go back and admit you were wrong.

Douglas is right about switching phase in a system. I am not sure though what would happen if you ran 180 degree out of phase channels into an oscilloscope. Interesting to try. 
@russ69, I hate to tell you this but the last thing you want to trust is your ears. Human ears and perception are not trustworthy in this regard. None of us can make the claim of having trustworthy ears. This is exactly why more rigorous testing methods are required to come to any reasonable conclusion. It is also the reason for the popularity of "Tweaks" It is also the reason many of us do not have to hear an item to know the claims are false such as the cable cooking thingy Douglas mentioned. The claims made for it are downright stupid. They embarrass themselves with such rhetoric demonstrating that they have no idea what they are taking about. Don't be shy. Call things out for what they are. I want my system to sound it's best like anyone else but I refuse to spend money on silliness when there are so many things to buy that might or will make a meaningful improvement. In evaluating equipment never trust your first impression. repeat the comparison over and over until you are sure. When you are not sure of a difference assume there is not any. If you can set up an AB comparison then by all means. I have several ABX boxes that I made in the early 80's that run on 12 volt relays and a push button switch that is not marked in any way. I have no way of knowing what side is on.    

Rather than hearing it from me simply google double blind listening or perhaps ABX. Try to put yourself in the position of the person being tested. 

So indulge me and tell me what exactly you would measure with the null tester and how this data could be in any way definitive.