Rereading the thread I see that srb posted that the receptacle amperage must match the circuit breaker amperage if it is a dedicated circuit. Canadian codes may be different.
My heartburn with the situation is that after looking at the manual the only place where I see a UL decal in the product photos is on the power cord made by Carol.
If this amp does consume more than 20 amps routinely it should have a different plug and definitely should not have a 15 amp plug. The photo does not show the plug since that is probably changed depending on the region that it is shipped to.
But these guys make a lot of amplifiers so they must know the rules.