life span/failure rate of filter capacitors?

@yoyoyaya 

It kind of depends on whether you believe in preventative maintenance or are a kind of fix it when it breaks person.

I generally like to fix stuff before it breaks.  Particularly stuff that might cause a lot of damage when it breaks.

@jasonbourne52 

Electrolytic cap lifespan is unpredictable! My Sumo Andromeda is still going strong while my BEL 1001 and GAS Son need new caps.

how much life is on the caps in those units you mentioned?

+1 kikanki 
If you want the amp to last, replace the capacitors. Have someone use higher temperature rated caps whenever possible. I have amplifiers that use components that are unobtainable so preventative maintenance is a requirement for me.

Note that loss of capacitance would result in poorer filtration and eventually an increase in your noise floor.

Nelson Pass is one of my audio idols, but I'm not sure his words are entirely relevant to the OP.  Cap lifetime may not be the same in tube & ss amps.  The energy is stored at a much higher voltage for tubes, ss power supplies hold a lot more charge.

Not all electrolytic caps are created equal. Some have high temperature ratings (good), higher mtf (good), higher ripple current (good), higher esr (bad). Thing is, each one of these parameters can be important, so try to find out everything you can about the caps you have, and specify a cap that is at least as good in every respect.

I buy all my electroytics from Digikey (no affiliation). Great company, tremendous inventory, next day delivery. And no surprises.