Kingwa says this on the site: http://www.audio-gd.com/Master/Master-9/Master-9EN_Use.htm
The rule of the power ON / OFF:
Power On :
Source power ON ----> DAC power ON ----> Master 9 power ON ----> Amp power ON
Amp power OFF ----> Master 9 power OFF ---> DAC power OFF ---> Source power OFF .,
I never knew that not doing this could damage your dac, though...
But from the above instructions it seems you can always leave your dac on??