Lifespan of a quality solid state amplifier?

In an interview the Chief Engineer at Bryston said that their amps are built to last 40 years or more. That's why their warranty is so good.

My class AB amp is on 24/7.
I subscribe to the thermal cycle philosophy.
I don't consider the energy wasted, I'm in my living room almost all the time I'm home.
Next April, when my AC is on for the first time, I'll box it up & go to Class D amplification, for the Phoenix summer.

Agree. To build powerful SS amp that would last for 40 years is challenge. Bryston deserves respect.

I've had a Marantz units (MA5) for close to forty years, which I use on a regular basis, never has need repair.

Any gear if used serves much longer that the one that used occasionally.