re capping

All capacitors dry out after awhile 15-20 years for sure 
Electrolytic power caps  for sure  . I owned a store and worked modding 
caps , there are several grades of quality  ,coupling caps,of various types like teflon, paper in oil.foils,  as well as  Electrolytic , including the top 4 pole cap types.  You get what you pay for  on average .

for the past 6 years i only use my equipment like 6 hours a week. should i worry about the 'caps'??

When it's time to change the power supply caps, your amp will let you know with a loss of bass definition soon followed by buzzing/humming. Until then, leave it alone if it works and there is no sign of physical damage.

And when it does so with a loud bang it is too late to save your expensive speakers.

Capacitor goes with loud bang because of avalanche effect. Capacitor is charged in narrowed current spikes of very high amplitude. That creates losses and heat with ESR of capacitor. When capacitor dries out ESR increases causing bigger losses and bigger temperature increase. Since temperature also increases ESR at one point it will lead to explosion. Because of that all electrolytic capacitors have some form of fuse. I agree with gs5556 - you will hear loss of bass definition and 120Hz buzzing way ahead of that.

or the past 6 years i only use my equipment like 6 hours a week. should i worry about the 'caps'??

Not for at least 20 years.