Oh, now I get it.
GFCI outlets do go bad, but it could also be equipment with a leaky capacitor to ground or a reactive load, which is most likely with bigger motors and amps.
If you find the problem is only your amp, I’d suspect swapping a GFCI won’t help.
Sometimes these trips happen intermittently, so hard to diagnose fully. Of course another alternative is to see if you can trigger any other outlet. Maybe take the suspect piece of gear to your kitchen counter and see if you can trigger one of those outlets.