[Amps] class "A" RF amp question

[kenw2dtc]

Bob said:

"If you say 50% efficiency in a class A (people can argue either side of 
this) You would need to heat up the shack with 3000 watts"

*******Would 3000 watts dissipation apply both to a 1500 watt PEP SSB signal 
and a 1500 watt PEP AM signal?

73,
Ken W2DTC