So, x838nwy, you thought that running your own DBT would somehow clarify the matter? No chance, this is just the beginning… of your nightmare.
Joe makes some thoughtful points, which I think are particularly valid if you need to know how the said component is to perform in a range of circumstances (essential for a designer) and I largely agree. However, every single variable in such a test will conspire to confuse your poor overworked brain. So if you just need to know if A is different to B, I think you need to try remove all possible variables , including your circumstance and mood (e.g. time of day).
I think that fast-switching DBTs are unbeatable at removing Expectation Bias, and excellent at instantly spotting gross tonal/colouration differences that you typically get with headphones (frequency response that looks like a cross-section of the Himalayas) . But the same tests are unreliable IMO at spotting more subtle-but-significant differences that you get with relatively neutral components like DACs and cables (ruler flat frequency response, negligible THD etc). Not imposible, just unreliable because of the mind tricks that have been fruitlessly debated a million times.
What this means is that if you run your fast-switching-DBT and find no difference between components A and B, I simply won't accept that result until you repeat the DBT in a longer term test, of a style that I would deem to be fool proof.
The only thing that can be completely guaranteed with such a test is that the side that disagrees with your end result will nit pick your method to death, and the side that agrees with your end result will quietly overlook the same flaws.
TheAttorney is giving you notice that he intends to obscure any result to the best of his ability, so better not to try. Your nightmare, at his hands, is about to start. The Internet, don't you love it?