First, your Adcom GFA-555 IS an audiophile component. I've had two for them for 20 years. You'll take them away from me when you pry them out of my cold dead hands.
All of your own ideas, and all of the suggestions offered above, sound reasonable. The question of whether to get a good used receiver (Denon 3805 comes to mind, if you can live with the weird remote) or go with a separate pre-pro is a tossup. The fact that you are on this website tells me that you will probably be happier in the long run with a separate pre-pro such as one of those mentioned above.
All of your own ideas, and all of the suggestions offered above, sound reasonable. The question of whether to get a good used receiver (Denon 3805 comes to mind, if you can live with the weird remote) or go with a separate pre-pro is a tossup. The fact that you are on this website tells me that you will probably be happier in the long run with a separate pre-pro such as one of those mentioned above.