Recapping your amp

Aluminum electrolytics can even go bad(via dielectric polarization), given enough time, on the shelf and unused(http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.823.6133&rep=rep1&type=pdf). Of course, heat and cycling, also take their tolls, but- if your component is older than 20 years, it’s virtually certain, the caps are due for replacement, even if(to the eye) they seem perfect.   Ears adjust to losses in fidelity, when that loss takes place over time and most won’t notice, like they would, were the change sudden.(http://www.elna.co.jp/en/capacitor/alumi/trust/) (https://www.illinoiscapacitor.com/pdf/Papers/Life%20expectancy%20of%20Aluminum%20electrolytic%20capa...) (http://www.powerguru.org/electrolytic-capacitor-lifetime-estimation/)

If you start hearing a 60-120hz hum when only the amplifier is on, then it is time for power supply caps to be replaced. Prior to that, you may hear a softening of the sound (transients and mid to lower bass).

If the amp is running and sounds normal, leave it alone.

If the amp is running and sounds normal, leave it alone.

I agree...I recapped some old speakers and never felt they sounded quite the same. 

Recapping loudspeakers is a thing that must be individually assessed in how it is done. Small bypass caps of a film type sometimes works (across electrolytic types), but if the crossover is originally all electrolytic, then the new should also be all electrolytic - unless one wants to get down to redesigning the crossover.

Let's assume;

You have a family car with timing belt, that according to the owners manual is supposed to be changed every 7 years or 100,000 miles.

Your car is 6 years 10 months old and has 70,000 miles. It was not a taxi, was cared for, and was not abused.

Timing belts give no warning signs before they go.

Are you going to get the timing belt changed in two months ?