Just to clarify: the ASIAir Pro is not able to power via USB only. If you use one of the 4 x 12V power output, as long as you do not pull more than 3A, all is fine.
If you want to use the 4 x12V output, you indeed need a power supply able to output max 5 A to 6 A, so you are not restricting one equipment if it need to pull up to 3A, while causing other connected device to see a low voltage.
For my setup, as I already had a PegasusAstro Pocket Powerbox Advance, my 12V - 5A is going to the mount (iOptron CEM40).
From the saddle 12V output, it goes to the PA PPBA, then to the ASIAir Pro.
The PA PPBA run the dew-heater in auto mode (as the ASIAir still enable to do that) and the 12V POE of the external Wi-Fi aerial (on leg mount).
The ASIAir Pro then has 12V going to the EAF and 12V going to the ASI533MC-P.
Two USB2.0 port on ASIAir have EAF and ASI462MC
Two USB3.0 port have ASI533MC-P and PA PPBA (as USB3.0 Hub)
The Mount USB direct cable and USB Stick are on the PA PPBA USB.
Never experienced lack of 12V output, even during GoTo cycles (most consuming event on setup).
