P = I x E
P = Watts, Volt-amps.
I = Current, Amps.
E = Voltage.
Will a 240V 1500 watt space heater connected to a 240V source produce more heat than a 120V 1500 watt space heater connected to a 120V source? No.....
Current, amps?
P / E = ?
1500W / 120V = 12.5 amps.
1500W / 240V = 6.25 amps.
A 120V 20 amp branch circuit is capable of supplying up to 2400 watts continuous power. The same branch circuit will supply short spurts, draws, of well over 2400 watts all day long without causing the 20 amp circuit breaker to trip open. If voltage drop is an issue, or concern, use #10awg branch circuit wiring.
Unless a piece of equipment, like a monster power amp, consumes more than 1440 volt-amperes continuous power it’s a violation of US electrical safety code to install a 240V branch circuit and receptacle in a US residential dwelling.
I doubt any manufacturer builds a home consumer sold amp for use in the US that is rated at more than 1440 watts, volt-amps, continuous power. They know the power cord plug needs to have a 5-15P 120V 15 amp plug if they want to sell the amp to a US home consumer.
NEC 210.6
(A) Occupancy Limitations. In dwelling units and guest rooms or guest room suites of hotels, motels, and similar occupancies, the voltage shall not exceed 120 volts, nominal, between conductors that supply the terminals of the following:
(2) Cord-and- plug connected loads 1440 volt-amperes, nominal or less or less than 1/4 hp.
Jim.