Power Supply for Nintendo NES and Super NES

The original power brick output AC but this console doesn't use it directly, it go through a rectifier and filter to produce DC. So it doesn't matter, if you give this console AC or DC. It will be converted to DC.

It is very common for aftermarket power supply to add noise on the video signal (RGB, composite or S-video) on old hardware. I experience the same problem when I first start retro gaming. I rigorously tested and selected a good manufacturer to avoid this problem so I can fully guarantee that this power supply will not alter the video quality.

My power supplies are modern switching power supplies, they are the multi-norm (110V and 230V) so you don't need to use a step-down transformer. I would even advise not using it specifically with these because most of the time the power supply will be directly on top of the step-down transformer which generates heat that would make the power supply thinks it's overheating and could trigger its electronic protection. You just need to choose a power supply with the plug of your country not the plug of the origin's country of the console.

No, you can't damage your console with this power supply, the console has a tolerance in terms of voltage. The original power supplies are unregulated, so the voltage indicated on the sticker is not real, it's just an approximation, the real voltage can vary around ±3V depending on the load. My power supplies are regulated, so the real voltage matches the sticker. After that, this voltage is regulated inside the console to create a working voltage (5V most of the time).

The current value indicated on the power supply is the maximum current the power supply can deliver, the console determines what quantity of current it needs, not the power supply. A slightly more powerful power supply has no impact and have no risk of damaging the device.