adcom gfa 555 vs 555 II

I am planning to buy an used adcom gfa 555.
I was wondering if I should buy gfa 555 or 555II.
Any of you heard the difference between these 2 models ?
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buy a used chiro c-200. much better amp than either one. i had both the mk1 and 2 recently and the chiro killed them both in every way. but if you must go with adcom, i think the sereis one was smoother myself. compareing the chiro to the adcoms , i will put it this way the chiro is high end , very comparible to a krell kst 100. the adcoms sound weaker . you can also buy chiros for the same money as adcoms. i have one as a spare and not one for sale so i am not pumping my sale. if you start spending more money then i might talk of other amps as well. good luck.
Kirk930 is correct. Chiro great choice, and actually I would tell you to look at the Bryston 3B if you have to have a "name" amp. Not as many watts, yeah, I guess on paper, but actually delivers a deeper bass, especially to a 4 ohm load. probably a touch more money, but I just saw one sell for $400 shipped from Canada, so they can be had.
Did you know that Adcom amps are good candidates for modding? I spent $300 to have a 555 hot rodded and have kept it (primarliy as a backup) while others have come and gone. Modding opened mine up and provided sonic benefits which far outweighed the cost of the upgrades.
i still think for the 300 extra you spent moding the adcom.why not buy a better amp. that puts you in the 700 to 800 dollar range. their are a lot of amps in that range . you can almost buy a krell kst 100 in that range. i have seen them as cheap as 995. the kst is a far better amp than the adcom. you can also for about 1200 range buy a sonic frontiers power 1 . you could still buy the chiro and have lots of cash left over. or like jiva says bryston. if you have a chance compare the adcom to other amps , you will see. anyway thanks for listening to me yap kirk.
I owned a 555II which I sold on the advice of Stan Warren, whom I called to inquire about modifying it. He advised me to buy the 5400 for modification because it has a better, more modern circuit design and components.(If you need more power, go with the 5800.) He explained his reasoning in detail, of which I retained almost zero, but the bottom line was the 555II was not worth modifying and the 5400 was. The modifications improved the sound considerably, and it is light years better than the 555II. I would suggest you not buy an adcom unless you are planning to modify it. Otherwise, look for a better brand as recommended above.