You do not power the amplifier with a pure sine wave. You power it with pure DC. If pure DC is coming out of your power supply using whatever comes out of your wall socket than purchasing any power source is a total and complete waste of money. If pure DC does not come out of the power supply of any electronic device than it's power supply is garbage and that piece needs to be replaced.
If you want to know what your power supply is doing just hook up an oscilloscope to it. You should see a perfectly flat line at the voltage spec of the power supply. Now that is a static measurement. The power supply also has to meet the demands of the device. If it is a power amplifier it has to be able to supply the power necessary to support the full specified output. There should not be a voltage drop. This is not affected by the cleanliness of the AC supplied to the unit.
If you want to know what your power supply is doing just hook up an oscilloscope to it. You should see a perfectly flat line at the voltage spec of the power supply. Now that is a static measurement. The power supply also has to meet the demands of the device. If it is a power amplifier it has to be able to supply the power necessary to support the full specified output. There should not be a voltage drop. This is not affected by the cleanliness of the AC supplied to the unit.