20amp IEC connectors are rectangle, 15amp are sort of triangle with one corner flatten off. Look at the shape of the opening where the power cord is connected to your amp will give the answer. 15amp IEC connector will not fit into a 20amp.
Do a Google image search for: Hubbell 20 amp IEC, you'll see what it looks like.
Good Luck
Scar
Do a Google image search for: Hubbell 20 amp IEC, you'll see what it looks like.
Good Luck
Scar