It depends on the Class A and whether it is tube based or transistor based but couple things are universally true.
They are horribly inefficient and run very hot. Due to that heat, they tend to require large heat sinks. They tend to be very heavy and power consumption is very high. Because they are so inefficient, they tend not to be that high power.
Sound profile is a varied as there are amp companies. I have heard Class A amps that are dark and warm and others that are bright and shrill. Tube amps vary as much as transistor amps and careful pairing with your speakers is still required along with plenty of ventilation.
They are horribly inefficient and run very hot. Due to that heat, they tend to require large heat sinks. They tend to be very heavy and power consumption is very high. Because they are so inefficient, they tend not to be that high power.
Sound profile is a varied as there are amp companies. I have heard Class A amps that are dark and warm and others that are bright and shrill. Tube amps vary as much as transistor amps and careful pairing with your speakers is still required along with plenty of ventilation.