I should admit that my test was not completely scientific.I would simply suggest that if you are actually going to compare the sound of two different DAC's, that you match levels and test without knowing what is playing. Without that effort, our memories of sound aren't going to be reliable. Not just for you...for any human.
If there are actual meaningful differences one can identify between them, it's likely that one is broken or there is some kind of impedance mismatch. Claims of audible differences abound...except when subjective tests are actually controlled...
Just trying to save you money chasing windmills...
Its not easy to do a blind test with matching levels.
I spent grands but other members will be able to save moneys.
Anyway I have a plan to test RME ADI2 DAC by headphone.