I am confused by the lack of comprehension regarding my question.
Well first you asked about DC, which is nothing to do with anything here.
Then you asked about voltage, with no reason, at least none anyone can understand.
The AR preamp is capable of higher voltage. Does not mean it is ever used. If you were saying your AVR volume is max'd out and still not enough to drive the amp that would at least make sense. But no. There seems to be no reason for any of your questions except as an exercise in what if's.
I would highly recommend the excellent The Complete Guide to High End Audio by Robert Harley, now in a new 7th edition. In it you will learn a lot about power supplies, which will answer a lot of your questions and if nothing else help you understand the subject well enough to not be so perplexing when you do have a question to ask.