When to get your amp up graded caps ???

3." Your willing to and can afford the investment compared to selling it and adding the cost of upgrading towards something more current"

"but I might upgrade it anyway when it seems (to ME)to need it, because that's what we do..."

Bingo

Filter caps last between 10-15 years. Life span is a function of the quality of the cap,(some are better then others), the ambient temperature surrounding the cap,( high temps. will lessen cap life, and how long the caps are left idle. Generally speaking, leaving an amp on all the time gives the filter caps an easier time of it. In most cases that's just not feasible. If you like the product, and want to make a nice improvement, especially in bottom end performance, replace the caps.

I own unit Classe 30 preamp that is almost 30y.o.
It hasn't gone through any recap or repair process although I checked-measured filter caps and tey've only lost 3..4% of labeled capacitance. Having perfect pro skill and instruments to replace circuit elements I'd prefer to be resourceful and keep healthy components up until later and enjoy the music. Usually it might happen all of a sudden that they will dry out. Than this will be audiable.