Also, for 4k these days you can stream in dolby vision and run optical to your old AVR in 2 channel, or to play 4k blue rays in surround buy a cheap 4k player and run hdmi to your old AVR and picture is still amazing but not 4k I guess. I'm more a sound person so I'm more impressed with the old players with high end dacs to play 5.1 blue ray audio than I am concerned about picture quality when I can alternatively stream and play 4k dolby vision. That is about the only constraint I can think of in using a mid 2000s high-end AVR (not having 4k + surround at the same time)]. If you looked at the features on one you might be surprised and how they upsample and do sophisticated processing and I'm not talking about cheesy DSP effects either. We are talking decoding dsd, bass management in the digital domain, 24 bit processing, and ability to handle a multitude of popular codecs. I'm sure dolby has some new thing but I haven't been particuarly limited on any media I"ve wanted to play to this date. These things are very deep monstrosities though weighing over 50lbs so that's another BIG constraint for most people. Lots of fantastic opinions and info in this thread. Thanks to the original poster for asking such a great question even if my opinion is in the minority.