After doing some research on both models here, it looks like technically, the Sony STR-DA777ES, despite being an older model, is still in many ways superior to even their newest models, such as the DA4ES. The 4ES is 7.1, I believe the 777ES is "only" 5.1. However, I believe that 5.1 is all I'll be doing for the near future...even so, I had hoped to just buy one receiver and have it last me for 10 years or more. Still, I see on Crutchfield there's an upgrade kit for the 777ES that upgrades it to 6.1 (it includes a CD-ROM, serial cable to connect to a computer, and new remote), so at least that's something, although at $130 it ain't cheap. But how would that even work, anyway? I mean you can't use a CD-ROM to add a whole other amplifier channel to a receiver... At around $800 for a new-in-box unit for a 777ES, vs. $640 for a brand new 4ES, which makes the most sense? The rest of the system won't be particularly high-end, at least to start. I'll probably be looking for a complete 5.1 speaker system for $1000 or less, for example, to get me started. I was all set to go with the 4ES, but upon seeing the 777ES offered new at this price, even though it's more than I really want to spend, I'm wondering if it will be so much positively better than the 4ES that I shouldn't pass it up?