If you want an idea of what one renowned amp designer/builder thinks about Class A, the heat it generates, the effect on the amp's circuitry, etc, I would suggest a read of an owner's manual of an early Pass Labs Aleph amplifier (available, for example, here). I would never have thought an owner's manual entertaining but it is. One telling excerpt...
The amplifier does not require any maintenance. While the design is conservative, this is a hard running amplifier, as single ended Class A operation is the least efficient operating mode. In fifteen years the electrolytic power supply capacitors will get old. Depending on usage, you will begin to have semiconductor and other failures between 10 and 50 years after date of manufacture. Later, the sun will cool to a white dwarf, and after that the universe will experience heat death.