It’s not. If you mean an extension cord with built-in ground and surge protection, that is.

If your amp had a ground in its power plug, we wouldn’t be having this conversation. If there is a surge in the actual power to the outlet, the surge protector might catch it. But since this is about surges inside the device itself, it means you should no longer actually touch the amp because you might get a shock. You can imagine that the higher the amperage flowing through the amplifier, the more dangerous this is.

I have only a very basic knowledge of electricity and an even smaller knowledge of amps but I have heard about certain amps that would be susceptible to immense power surges which would short out some circuits and that power needs to go somewhere. If it’s not grounded properly it might release its current into the air where it’ll find you, or maybe catch fire.

The specifics of this and why or how this happens should be findable online.

Most likely it’ll also have something to do with the higher voltage direct current being transformed into a lower voltage alternating current. But why and how you’d need to be properly grounded for that is beyond me.

The dangers are limited unless you hit an edge case which you’ll want to avoid. In other words, you’d have to be really unlucky. Surges can happen with audio equipment easily though.

The principle of grounding is actually simple enough: when something goes wrong with the current, for instance if it can’t move through the wires it should move through, it’ll try to escape. Grounding makes sure that it moves through a dedicated wire to somewhere it can no longer do harm. Cars, for instance, use their frame as a ground, which will conduct the current into the tires and into the ground (ie Earth) if necessary.

This is probably 25% accurate so I’ll invite any electrician to correct me but I am fairly confident this will do as a basic answer.

You hook up the GND contacts to anything that is not connected to anything electrical, preferably something non-conductive at the end of it, you’ll be fine.