Lifespan of a quality solid state amplifier?

Background noise like a hum is the biggest sign caps might need replacing. If the amp hasn't been used in awhile you should bring the voltage up gradually with a Variac. If you just plug it in after a long time it can cause a failure of the capacitors.

Digepix:

Thank You.

Bifwynne, 6 months is nothing. You can safely plug it in. Caps go bad after at least few years unpowered.

I get the picture. Well-made piece should last at least for 50 years with proper use and care and with maybe some not very big repaires every 15 years or so. That's pretty good. And tube amp should last 150 years, I would guess.

Kijanki, can I power up the amp without a load or input signal? I've heard that it's best to have a load with tube amps. Different beasts of course, still better to ask.