Lifespan of a quality solid state amplifier?

I am still (as a backup) using some 25+ year old SS amps and they still work fine other a higher noise floor due to aging caps in the pre/amp sections. While I don't think this is unusual, I would say the most amps of either SS/tube nature are pretty reliable. Other than tubes themselves, the main components that age are the capacitors. Strangely two factors can effect their longevity, one is heat-which would logically take a bigger toll in tube amps or class A biased higher power amps. The other killer is lack of use as the caps will dry out. Many people advocate using a Variac to bring power back to an amp that has been idle for an extended time to bring the caps back up to life slowly as a sudden rush of current could blow them. I've also noted that amps with several smaller output caps (as opposed to fewer but larger caps) are less susceptible to aging -don't know why...

Spinaker01 - Drying of the electrolyte increases ESR of capacitor. When it gets into many ohm range it becomes very audible and after that it might even go to thermal runaway since current going thru cap x ESR = Heat but temperature increases ESR (positive feedback). Smaller caps are connected in parallel making ESR lower to start with - less audible when old.

Each 10degC of temperature increase cuts life of capacitor in half.

Electrolyte inside of a cap eats out aluminum oxide (dielectric) lowering breakdown voltage. Presence of voltage rebuilds this layer.

I always change the electrolytics when I buy used. When they get tired, the music gets tired.

Between my buddy and I we have 3 SS amps still going strong after a combined 75+ years. All of them are 200WPC and up. Adcom, Kenwood, and Carver. The only issue is noisy volume pots on the Kenwood but I leave it at full volume all the time anyway so it is not an issue. Even the meters still work on the Kenwood and the Carver.

Kijanki, got a question. As I mentioned above, Crown rehabed my DC300A about 6 months to a year ago. I keep it around as a back up amp, but haven't turned it on since Crown checked it over. Per your post about caps drying out, can I safely plug the amp in without an input signal or a load just to get some juice running through it?? Will that keep the caps healthy?