My old GFA 555 went unpowered for years, but it always worked as it should.
The Mk II, should be as good, considering it is a few years younger. If you take off the top cover and look around for anything unusual-like something distorted or bloated, then I think you are good to go.
The only thing that can affect the amp are leaking capacitors, and those are pretty obvious on casual inspection.
Nelson Pass did a great job designing the 555, so I doubt there is anything wrong, especially if you bought it from a dealer-who should have tested it before selling it.
I believe Musical Fidelity does upgrades to older Adcoms. Another route to go, if you wish...
Bob
