Class 1 or Class 2 electrical safety connection i.e.must be grounded or not?
Is the amp Class 1 (mandates a mains earth) or Class 2 (double insulated)? If double insulated the mains socket can only have 2 pins (like a fig-8) mains cord. Also Class 2 will (definitely should) show a printed symbol near the mains input of a box within a box.
Most Japanese-made audio equipment is Class 2 with no connection to the mains supply ground at the wall socket, as for example, a hair dryer would be for obvious safety reasons.
Whilst double insulated is great from a safety perspective, it does have the audio consequence of not having that inbuilt ground drain in the mains cord.
Alan A. Shaw
Harbeth Audio UK