OK,,, if you say so but as there are only two wires exiting the mains cord (Brown & Blue) then it's highly unlikely that it is earthed.

Normally the Earth wire (Green and Yellow in my country) goes direct to chassis and bolted with a lock washer.
Another thing that may not be obvious is the use of Step down Tx's.
Although the 240v side is Earthed some units don't carry the Earth through to the 120v output and that can go unnoticed until someone gets zapped.

If it were my amp I'd be checking there was continuity between Earth pin on cord and Chassis. Only takes a quick check which could save your life.

The Earth pin/Chassis continuity is the first thing I check when I open an Amplifier.
Stay safe, Phil.
(Never rely on visual inspections)