I have a G-Major 2 and the housing is always warm, even if the power switch on the front panel is off. Is this normal?
Yes this is normal.
The power supply is on as soon as the unit is connected to the mains power. The front switch is actually more of a standby switch. The unit can remain connected to the mains - it is not a problem if the unit gets warm - but we recommend to use the standby switch when it is not in use.