Hmmm. I'm actually more concerned that you will be able to get clean, safely isolated connections soldered to the HDI-30 pins.
Someone else will be able to correct me if I am wrong, but I think you can take +5v power from the serial or floppy ports of the Plus without major impact on the power supply. Have a look at the pinouts. http://68kmla.org/files/classicmac2.pdf
If you wanted to take power from another Mac, that should work without issue as I've done it for a variety of peripherals, including running a CRT on one Mac with the flyback transformer of another. The same mains power supply shouldn't matter as long as they connected to the same ground circuit, i.e. the same outlet. Heck, that shouldn't even be an issue, but I'm no electrical engineer.
Someone else will be able to correct me if I am wrong, but I think you can take +5v power from the serial or floppy ports of the Plus without major impact on the power supply. Have a look at the pinouts. http://68kmla.org/files/classicmac2.pdf
If you wanted to take power from another Mac, that should work without issue as I've done it for a variety of peripherals, including running a CRT on one Mac with the flyback transformer of another. The same mains power supply shouldn't matter as long as they connected to the same ground circuit, i.e. the same outlet. Heck, that shouldn't even be an issue, but I'm no electrical engineer.