I am no expert, but I think turning on the amps will not be a problem.
If you are concerned, take off the cover and look around. If you see something bulging or looks like it is drooling, then you have a bad cap.
If not, they should be fine.
I owned an Adcom GFA-555 for over 30 years before I sold it, it worked like it did the day I bought it.
Considering that you haven't used it, and hopefully stored it in an area without extreme temp/humidity swings, I doubt it would need caps replaced.
I would sell them and tell the buyer the history, and let them decide the need to recap the amps.
Bob
If you are concerned, take off the cover and look around. If you see something bulging or looks like it is drooling, then you have a bad cap.
If not, they should be fine.
I owned an Adcom GFA-555 for over 30 years before I sold it, it worked like it did the day I bought it.
Considering that you haven't used it, and hopefully stored it in an area without extreme temp/humidity swings, I doubt it would need caps replaced.
I would sell them and tell the buyer the history, and let them decide the need to recap the amps.
Bob