V-DAC Power Supply question.

Sorry for the question but I know nothing about power supplies.

Why are people using the Pyramid PSU which is 13.8 V and 2.5 A when the original PSU should be 12V 500mA?

And why is the Pyramid advertised as 12volts 3amp?

I need to upgrade the power supply (I have none atm) but I'm a bit confused about the voltage and amperage.
i don't have the technical answer and wonder about this also. i started using the pyramid ps-3kx 3 months ago and it sounds great. not a huge change but i don't like the wall wart and music fidelity's power supply was too expensive for me. you probably know this but check the polarity before hooking the unit up if you do get one. don,t trust the lettered cord because mine was opposite what some might think due to the lettered cord being negative.
13.8 volts DC is a commonly seen power supply voltage because it corresponds to the nominal output voltage of a six-cell lead acid battery when fully charged. Equipment that is specified for 12V will usually work fine on 13.8V, at least if it is well designed. It might violate the warranty terms, though.

Having greater current capability than the requirement (2.5 amps instead of 0.5 amps) can't hurt, assuming that the quality of the power supply is not compromised, and its cost is not increased unreasonably. The load (the V-DAC in this case) will determine how much current is drawn.

For the PS-3KX, 2.5A is the continuous output current rating, and 3A is the "surge rating" (the rating for brief peaks in current demand).

-- Al
So from what Almarg says, it would be safe to use the Pyramid PS-4KX.? Output voltage is still 13.8VDC and output current rating is 3/4A. And the V-DAC will regulate the current draw?

Concerning current:

The PS-4KX, with a 3 amp continuous current capability and a 4 amp short-term current capability, will be just as compatible with a load drawing less than 500 ma as the PS-3KX is. The load device (the V-DAC in this case) determines how much current is drawn, based on its design and on the applied voltage. Using a power supply that is capable of supplying more current than necessary (in this case, a lot more) won't hurt.

Concerning voltage:

I have no specific knowledge of the design of the V-DAC, but well-designed equipment that is nominally intended to work with a 12V supply will commonly also work reliably at 13.8V. And that is further evidenced in this case by the reports of successful use of the V-DAC with the Pyramid PSUs.

-- Al