i want my arcam black box 500 to sound as good as high end DAC please help

Hi!

Probably the first what you can do is relative simple.
Check the PS caps, try to use higher quality (Elna, Black Gate)
You can have more attention to digital PS (ok, also for analog).

Those can be the first steps.

Later on you can turn to more difficult modifications (eg. upgrade the clock, add separated transformer and regulator for analog and digital, etc.)

BR,
Milan

PS: I have already mentioned the EIC socket in your other thread