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

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.  

Null test - you play sound 1, then sound 2, and subtract one from the other. If you end up with zero the sounds are the same. 
Example here shows that all cables (let alone new vs burned in versions of the same cable) are the same: https://audiofi.net/2019/01/audio-engineer-claims-his-null-tester-settles-the-debate-on-wires/

By Helmholtz acoustical science which he contributed greatly to found , only a few inches straw can transform a room in an acoustic paradise or in an acoustic hell... A single straw can make a costly amplifier sound bad and a bad one give a better result... Did you know that after installing hundred of systems?

I installed only mine and i learned that.... Do you know the cost of a straw? Peanuts.....Sometimes what is important is not the branded name of the amplifier and his price, but the precise lenght and location of the straw....This is my first lesson in acoustic....It is free😁😊😎





What you call useless "tweaks", useless costly secondary addition to a system are in fact SOMETIMES essential devices making the system able to work at his optimal peak... The only problem is that many are too costly for me... I decided to create mine.... I called them controls over the 3 working embeddings dimensions of a system... I never bought anything, i sell nothing, i created all my devices homemade at no cost...My 500 hundred bucks system fill my room 3-d with imaging, encompassing listener soundstage, natural timbre perception, in 2 main listening positions...Is there better one? Yes, but i will let you guess their price....It is not 500 bucks....It is the embeddings controls not costly electrical design ONLY and MAINLY the road to a good sound....

Am i hallucinated? Am i a liar? For some here deluded by dogmas probably... It is not the PRICE paid who give us good sound , it is the way we are able to control our system, the electrical grid, the vibrations and resonances, and tune the room...


Some people are incredible and even repeat here that our ears must subordinate their power to any objective number they will see on a dial....If they are doctor they call ears impressions " illusions".... And incredibly they listen to their system and call what they hear "good" because the equalizer said so.....

I will mute myself astonished by human voluntary blindness because of sheep walking.....

Dont buy and dont plug and play no more, be creative think and listen .....

Dont upgrade anything before everything is rightfully embedded in his 3 working dimensions and under controls...