Capacitor wear is primarily a time and temperature issue.
When used in pulse power supplies, the max ratings on current or amperage of the given capacitors, then those can come into play in the issue of aging. (besides the time and temperature issues). Capacitors have specs, like a max rating, and then age related data under those max conditions.
Capacitors in pulse power supplies, or in class d amps, are 'hit hard' continuously. Kinda like running a engine that has a 7,000 rpm 'red line'..at the max rpm of 7,000 rpm..continuously. Always. forever. the end won't be long coming. Maybe a day or two, for the engine. If it makes it that far.
Kinda like beer storage. Cool, dry, dark (no light/heat exposure)...and this leads to a long capacitor lifespan.
Units from the mid 2000’s can be bad from over-stressing and some 1980’s-late 1970’s capacitors CAN be fine, but 99% of them aren’t. That’s just vintage buyers and sellers fooling themselves that ’all original’ is a good thing.
Generally, anything over approx 12-15 years of age needs to be assessed. Depends. Depends on the specific example.
Ie, digital or class d amps, which are always over stressing their capacitors in their power supplies.
How many horror stories are there of 5-10 year old subwoofer amps that are broken? thousands and thousands.....
soon.....The electronics wear down ’butchers bill’ will begin coming due on all these new fangled class d amplifiers out there, these days....
conventional old school power supplies, known as 'linear power supplies', they age well. Those are built to last, in design and execution of the build.
Modern pulse power supplies are junk, in the realm of longevity.
Note that 99.99% of all class D amps and subwoofer (plate) amplifiers are built this way and are essentially ticking time bombs in the expected lifespan department. small, light, efficient..well..there is a price to pay. It's a case of quality drift being fast and high and a short lifespan. Which is perfect for the big corporate game, the end point and short lifespan is built right in, so you can get on to buying a new model in fairly short order.
Pulse power supplies have crept into so called 'high end' gear, and I'm not sure it's a good idea at all. But, what the heck, the speed of change in the digital end of the market is so fast, that some of that digital stuff is technologically disposable in 5-10 years, like the the $29 DVD player from Walmart.