I am now on my 3rd HK. Had an AVR 235 that I upgraded to an AVR 254. My 254 was recently fried in an electrical storm so I upgraded to a 2650 (was hard to pass up at $450 new shipped).
Honestly, I was expecting more of an upgrade from the 254 to the 2650 than it was...I was expecting the same difference I saw between my 235 and my 254. The 2650 is more powerful than the 254 for sure, but for 100% certain it is not the advertised 45 watts/channel more powerful. It might be 20 watts/channel more. Remote is the exact same, menus are exactly the same. In all honesty, I should have probably saved a couple bucks and scored the 3600.
In the end, I like the 2650 better than my 254 - I'm just disappointed it wasn't a bigger improvement. Sound quality, it sounds just as good (great) as my 254 sounded. All of my HK's have sounded great.