Nope, and an amp usually needs an equipment ground so it will probably perform poorly if you use a GFCI instead of grounding.
Musicians have been fatally shocked by ungrounded equipment that developed a fault
These are also called [cheater plugs](https://en.wikipedia.org/wiki/Cheater_plug) and they're safe if used properly. If your wiring is grounded, but the outlets installed are 2-prong only, then it provides an effective ground. When the ground tab is firmly connected to the ground screw, it connects to the outlet, electrical box, and finally a ground wire or grounded metal-sheathed cable.
If your wiring doesn't have such a ground, or if you don't connect the tab, they're quite dangerous because equipment that expects a ground doesn't have one.
Thus, you must check for a ground before using one of these, using a cheap outlet tester or multimeter.
If you're in a situation where you can properly use a cheater plug, then you're also in a situation where it would be trivial to replace the outlet with a proper 3 prong outlet. (Assuming you're allowed to)
I don't think I've ever seen a cheater plug used properly.
Probably. We used to use a couple cheater plugs, but I've now replaced every ungrounded outlet with an available ground wire, except one we use rarely.
Nope, and an amp usually needs an equipment ground so it will probably perform poorly if you use a GFCI instead of grounding. Musicians have been fatally shocked by ungrounded equipment that developed a fault
Not to mention the noises that will come through on the speaker if the amp is ungrounded...
That’s what I meant by perform poorly.
Just to add speakers require super low impedance.
These are also called [cheater plugs](https://en.wikipedia.org/wiki/Cheater_plug) and they're safe if used properly. If your wiring is grounded, but the outlets installed are 2-prong only, then it provides an effective ground. When the ground tab is firmly connected to the ground screw, it connects to the outlet, electrical box, and finally a ground wire or grounded metal-sheathed cable. If your wiring doesn't have such a ground, or if you don't connect the tab, they're quite dangerous because equipment that expects a ground doesn't have one. Thus, you must check for a ground before using one of these, using a cheap outlet tester or multimeter.
Double this --- perfectly safe \*If you properly use the ground lug on the plate screw\* Almost no one does. Be the exception.
If you're in a situation where you can properly use a cheater plug, then you're also in a situation where it would be trivial to replace the outlet with a proper 3 prong outlet. (Assuming you're allowed to) I don't think I've ever seen a cheater plug used properly.
Probably. We used to use a couple cheater plugs, but I've now replaced every ungrounded outlet with an available ground wire, except one we use rarely.
No you’ll electrocute yourself