Electrical Question - dumb one - but a good one

Also, judging by the wording of your question it's possible that the existing receptacle is already a 20A receptacle. 15A plugs can be plugged into 20A receptacles, but 20A plugs physically cannot be plugged into 15A receptacles.

A modern 20A receptacle looks like this. A 15A receptacle does not have the horizontal t-slot.

Re retrofitting the existing cord, obviously you have to make sure that the gauge of the cord is adequate to support the current drawn by the new amp. And if the gauge is not adequate to handle whatever the code requirement is for cords that have 20A connectors, it's probably not a good idea to use it because it might be used in a wrong application in the future.

Regards,
-- Al

The current rating is based on overheating if the specified current is carried continuously. A 15 amp rated plug will handle any current surge that your amp will demand just as well as a 20 amp plug.

no, your 3-prong plug is fine, you just need to change out the bit at the component.

you can also get adapters that will convert a 15 amp to a 20 amp if you want to try out the cord before you mod it, i've found that using good adapters on power cords doesn't do much negative...

good luck!

The power consumption of any electronic device is in VA.
This is corrected for power factor.
You get BILLED for watts, or KWH (kilowatt hours) but consume VA, which except for a resistive load is always higher. Power companies will bill large, typically industrial users slightly more (surcharge) for such low PF loads.

What does the plate say on the equipment? In general, I'd be reluctant to convert a device with a 20amp connector to a 15 amp service. If this is a large power amp with 'ample' capacitance, you may get a pretty good turnon surge, even if you never crank it up or have higher sensitivity speakers.

The wall receptacle is fine as is. Putting a 20 amp receptacle in the wall will change nothing current wise,but will give better grip on the prongs . Get a new chord that is 20 amp iec at the unit end. Only reto fit if your sure the cable is rated for it like Al said. Cheers