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.
