If you are going to choose another Adcom to replace your GFP-555II, I would recommend only the Adcom 5802. The 5800 amp was not one of Adcom's better amps, which is why it was replaced rather quickly by the 5802. And, while the Acurus A200 is an adequate amp, I would not recommend it given the other choices that are available right now.
After you decide if the Adcom 5802 will fit your budget, and will fit in the space you have for it (it's a tall amp, so check this factor out), you should consider some of the other amps in a similar price range, such as the Bryston 4B-ST (for my money, a better amp than the Adcom 5802), and the comparable amps made by Rotel, Parasound, and B&K.
I don't mean for my comments to sound like a condemnation of Adcom. I have owned a number of Adcom amps, including the original 555, and the 555-II. The current Adcom 5500 is a perfectably respectable amp in its price range, but the competition has gained a lot of ground on Adcom over the past several years. If you are going to upgrade your amp, then make the upgrade one which will offer you a real increase in audio performance.
After you decide if the Adcom 5802 will fit your budget, and will fit in the space you have for it (it's a tall amp, so check this factor out), you should consider some of the other amps in a similar price range, such as the Bryston 4B-ST (for my money, a better amp than the Adcom 5802), and the comparable amps made by Rotel, Parasound, and B&K.
I don't mean for my comments to sound like a condemnation of Adcom. I have owned a number of Adcom amps, including the original 555, and the 555-II. The current Adcom 5500 is a perfectably respectable amp in its price range, but the competition has gained a lot of ground on Adcom over the past several years. If you are going to upgrade your amp, then make the upgrade one which will offer you a real increase in audio performance.