|True Class A AFAIK has to either dump heat in the voice coils of the speakers or it dumps it into the heat sink. So if it is designed to run in class A for 100w, the 100w must be dissipated somewhere continuously. That's the heat coming off a 100w light bulb!|
The actual class-a device must dissapate the full output power it is capable of all the time.There is no "idel" current spec then"output current" spec because the idle current IS the output current !
This places a huge stress on the device being called on to provide this current so for a 10W class-a amp the heat sink area would be equal to a 200W class A/B amp because even though the A/B amp can produce 200 ultimate watts it does not do this all the time and in fact may do so for a fraction of a second once a week if layed all day and all night.The trasistors are idleing until called on and then only for one half of the audio signal so 50% of a % of the signal.
If your car was a class A amp it would be like putting it on a dyno and pegging the gas peddle to the floor and holding it there where AB would be your engine idling at a red light ready to go but not using any real power until you hitr the gas then the power in relation to how far you push the pedal