Thanks for your reply. I have been leaning that direction - to roll the dice again and try the HK. I take it from your response that there is a bit of a difference in sound between the two receivers. I guess I like the coloration of EQ and the Dolby sound when it helped with room issues, even with 2 channel music. I try listening through direct now and then and always end up going back to EQ, Dolby volume, or YPAO on the 663 which all sound richer to my ears. The easyset EQII on the 7550 sounds like it may do a better job that the original EQ that was on the 3600.
6ave has a great price on the 7550 right now, it is only a bit more than I could get the A-2000 for. Return policy is only good for replacement of the same item though. Not confidence building there. I returned a 2600 for a refund with JR a few months back.
It does seems that even though the 7550HD is a couple years old it still has pretty much what I am looking for - except for the quality question. Love that sound - but HK has really dropped the ball on dependability. Its a major hassle to deal with a defective unit - I know, I'm two for two in defective units with HK. Says a lot that I am even considering trying again. If only HK would work quality as well as Yamaha does. I'd not even hesitate a second. I'm grateful that I have choices and I'm confident that I will end up with the right receiver. Thanks again Phantom52