Do ALL the caps at one time when you decide to have them done.
Twenty years is a safe period.
It might not be neccessary to have all of them done then, but better that, if you really like the amp, then have one blow up on you suddenly.
I you want to do them early, no problem. Especially if the company is still able to do it for you, instead of some third party.
Think of it this way: if you do them now, that gives you 20 MORE years of service from now. And in four years, heaven forbid, maybe they will not be able to redo them for you.
Twenty years is a safe period.
It might not be neccessary to have all of them done then, but better that, if you really like the amp, then have one blow up on you suddenly.
I you want to do them early, no problem. Especially if the company is still able to do it for you, instead of some third party.
Think of it this way: if you do them now, that gives you 20 MORE years of service from now. And in four years, heaven forbid, maybe they will not be able to redo them for you.