Amplifier product specific can find IEC60065/UL60065 standard or GB8898 standard 10.3 look.
There are standards available for download at http://www.angui.org/index.php?u=16230
or Baidu library.
Specific voltage
For general input between 100-240V amplifier
Input to the shell depends on your shell is not metal material, the shell has not connected to the earth.
If the case is metal and connected to the ground, then generally 1500Vac/1min can be used.
If it is non-metallic shell, the general playing 3000Vac/1min
Transformer between the first stage is generally 3000Vac/1min, between the secondary is generally not required.
Of course I am talking about type testing, which is equivalent to sample testing, if it is a routine test, it is in the appendix of the standard.