What is the lifespan of a good SS Amp

Consider to go for a used SS Amp.
Around 4-5 years old.
Wonder how long one good SS Amp lasts.
I know that some 20 yo tube amps cost more than their
original retail price and they may last for centuries
(just need tube change)
but wonder how it is with the SS.
If I go for 4-5 yo SS Amp will I be able to enjoy it for a long years or after another few years it will start giving me problems.

Thanks for your help.

They last forever basically.
I have a Sansui AU-717 (late 70's) still going, just like the bunny.

With proper maintenance a solid state amp's life is essentially unlimited too. While it's true transistors wear out and capacitors can go bad, these things can be replaced in a solid state amp just as parts may be replaced in a tube amp.

I had some custom Quad current dumping (transistor) amps that were modified by Steve McCormack (McCormack audio) and they were wonderful for driving subs. After years of use I ordered all new Motorola output devices and replaced them myself.

The results were instant and very gratifying. Like new performance again and actually not all that much expenses to put it back right.
A well made solid state amp should last at least 15 to 20 years. A 4 or 5 year old solid state amp should last you at least another 10 years. I recently had two capacitors replaced on my Acoustic Research Amp, which I bought new in 1969(!!). Actually, the amp developed audible problems late last year, but I didn't get around to taking it in until last month. (Perhaps it lasted such a long time because I have been playing more my newer equipment for the past few decades.)
My two McIntosh 2105 Amps are still going strong after 32 years of ownership, and they've never needed service. Never even had a lamp go out, but I did decide to replace them all about 5 years ago. Mark
Depending on the particular design either transistor or tube amps usually run for at least a few years, and can be repaired indefinitely, so long as parts are available.
Tube amps tend to deteriorate so gradually that the user often doesn't realize it. Transistor amps tend to quit abruptly. Tube amp reliability is degraded by the high voltages that the circuits require and by the heat which tubes generate.
I have a Harman Kardon int amp purchased in early seventies that's still operational. Pots and switches a little scratchy but if it's in the garage who cares? Had to replace an output transistor, actually one of those output packs they use on less expensive amps.
I have pair of Meridian active speakers that have astounded me for almost 30 years and the amps have never missed a beat let alone been serviced.
Maybe new caps would be an idea but then they might blow away my good system.
There are too many variables. If properly ventilated, & not continually operated @ rated power, 20 to 30 yrs. isn`t beyond the pale.
Electrolytic caps (the big power supply caps are the primary ones) tend to dry out after 12 - 25 years. Higher operating temps usually result in quicker decline but there are differences among capacitor manufacturers too so it is difficult to generalize. Occasionally you'll see early failure or caps that last beyond 25 years but the above range covers "normal" situations. The electrolytic caps may loose storage capacity before total failure. Replacing these caps will usually cost $100 - $400. The rest of the components in SS amps are likely good for at least 50 years. The caveat is that some transistors are no longer available so if you have catastrophic failure you might be in trouble.
Well, if Bryston guarantees the many thousands of amps they have out in the world for 20 years, then you can probably use that number as a good baseline.
Atma-Sphere has a 20-year design rule for the simple reason that 20 years is about as long as you can reasonably expect filter caps to hold up. After 20 years, even if they have not failed outright, it is a good idea to replace the filter caps anyway, regardless of the technology of the amplifier or preamp.

A friend of mine was a big Cello fan but one day the unit was making a thumping sound. I checked it out and a filter cap in the regulator had dried up. For guys like me the days when Cello was in business is not that long ago- so you can use that as a yardstick for what you are up against.

One further note- if the unit has sat in a basement or garage unused for more that a year the filter caps should be replaced regardless of the age. Caps don't take well to sitting around without a charge on them, much like a battery! So if the unit has been sitting a long time it should be regarded as suspect even if it is not that old.
This is an interesting read. I have a White Labs a100. It has a problem not mentioned,so far. A transformer on one ch. has quit. So far the price has been to high to replace, because both transformers 'should' be replaced. I'm just guessing,I figure this to be of mid 90's vintage??(Which are far from 20 years of service)
I bought a Sansui AU6500 integrated amp, new, in Sept. 1974. Over 30 years later, it is still going strong, only problem with it is the little orange LED to indicate it was on burned out about 25 years ago. As a matter of fact, the amp is doing duty at a Cold Stone Creamery ice cream store about 11 hours a day 7 days a week providing music.
I own a Jeff Rowland 302 amp."It's a proprietry digital switching power circuitry amp and not a class D amp", in the words of one Stereo Times reviewer. Jeff calls the circuirty MECC (Mutivariable Enhanced Cascade Control). This amp hardly even gets warm. I was wondering what kind of longevity this type of amp would have?
Their going to outlive us unless they operate in pure class A.
They could last close to a lifetime. I am still using my Marantz 2285 solid state amp in the basement from 1978! Other than some bulbs being replaced and a good internal dusting and cleaning its still going strong!