The dead cap issue is tied to thermal and electrical stressing and some amps are anomalies that only appear over time. EG, I’ve got more than a few 30-40+ year old amps where the main filter caps measure and look fine. that is usually the rule, but when they get that old, new main filter caps are generally a good idea.
When I look at an amplifier, I look at many many photos of it and specifically the ones called ’nudies’, where you see the innards. Those images can provide some info on potentials in longevity but only to a knowledgeable and practiced eye.
The second point of research involves looking for any issue with repairs, if the unit (specific model) has repair issues, if the unit has a history of repeats in a given fault mode. People talk about refurbish or rebuilds and so on. Read the tech talk, even if it is a bit difficult to follow, it can be enlightening.
A check on the Parasound products will find little to no blips, trends, or anomalies in these areas. Always a good sign.
To think that one has to consider Parasound product age as part of an evaluation of a potential purchase....is a point in pride, not a problem. Pride in that the product has been around long enough that such age issues can actually arise.