Husk01: "Are there any Class A amps that do not run hot?"
The answer is no. An amplifier biased in class A at it's theoretical best is 50% efficient. This means that 50% of the power delivered by the amplifier is dissipated as heat. In the real world however, efficiencies run from 15% to 25%. The worst case for a class A biased amplifier is when there is no input signal where all of the power is dissipated as heat. Such is the price we pay for zero crossover distortion.
The answer is no. An amplifier biased in class A at it's theoretical best is 50% efficient. This means that 50% of the power delivered by the amplifier is dissipated as heat. In the real world however, efficiencies run from 15% to 25%. The worst case for a class A biased amplifier is when there is no input signal where all of the power is dissipated as heat. Such is the price we pay for zero crossover distortion.