What are the advantages to a Class A amp & what are the trade offs?

Typically more expensive per watt of power, higher energy consumption, hot running and requires adequate ventilation, can require more maintenance due to the internal heat build up.  Class A amps tend to be big and bulky.

As for the difference in sound when compared to other typologies, that is subjective. 

+1 testpilot

While Class A has it's fans, there is a lot more that goes into the design of an amplifier besides the heat and power wrecking that it does!


The truth is you need to hear for yourself on your own speakers to tell if it is worth the heat, weight and operating costs.


Modern solid state designs run Class A for most of the time you are listening anyway, so, arguably, the tech no longer matters like it used to.


Other factors, like having no feedback, are often bigger sound drivers. 

Best,
E

The old school answer of course, was that Class A has lower distortion through the zero volt crossing region.

How audible that is anymore though.... I don't know.