According to me this is a hardest question regarding HD500X.
I hope to see a satisfactory answer from someone experienced.
Each amplifier is different , but in my opinion it is important to answer what kind of setup should be installed when you are going to clean amplifier, then the case of a few standard patches explained how to adjust each parameter separately.
I do not know the answer :( and I have a problem to achieve a satisfactory sound with similar amplifier like yours.