I spent the last year farting with cables and the last six months tube rolling and one thing I learned is quick A-B testing does nothing but add confusion and force a quick decision. When buying a new input tube (Makes the most difference in the sound signature) I would install the new tube and listen and then replace the old tube back into the amp. This did nothing but confuse me as I could hear a difference but I could not tell exactly what that difference was. Spending more time with each tube afforded me a much better understanding of what each different tube sounds like and what it has to offer as far as the sound signature. When I bought my Dac I could tell the difference between non-upsampling and 24/192 but I was unable to tell the difference between 24/96 and 24/192 until I had the Dac for about a month and listening to my favorite tracks.
Here is a Monet painting I chose because it is complex.
If I made some subtle changes, nothing big mind you, would hanging this painting on the wall in the living room for a month or two increase your chances of discovering the changes as apposed to doing an A-B comparison where I flashed pictures at you and asked you to pick out the altered picture? I submit to all the Blind testing people that they are right, blind A-B testing usually confuses people and makes it very hard to make an educated choice. Stereo equipment however, is something we live with and spend many many hours with and I think giving a piece of equipment a fair shot at pleasing you in the long run is so much more productive than dismissing said equipment based on quick decisions. I think this is why so many people do so much equipment swapping, "I bought the AKG 701's for the third time" is a common thing to read in the forums. Anyone can fool people by forcing a rash decision, there is no Science there.
DBT is soooooooo ridiculous for evaluating audio equipment and is only ever entered into a discussion by people who just dont get it. Seriously.