4 and 8 Volt are used to power directly power terminals, both 2 volt (rca) and 4 volt (xlr) if the dac is connected to an integrated or preamp.
This in principle.

Funny...
if I could understand how you just explained it? I would not need it explained.

4 and 8 Volt are used to power directly power terminals...
Power terminals? I thought that speaks of OUTPUT level from the preamp to an amp, or another component. Not, as being used as some external power supply as you just made it sound. What is it you were telling me? I am wondering in what applications someone would need those doubles output levels.
I have a DAC 10 on order, and would like to understand this feature, please. Never seen this option before.
And, I am sure there will be others who also do not have a clue. I would like to be able to discuss with others this DAC/preamp, and be able to explain it.