Do you have any major electronics stores in your area. When I bought my Onkyo awhile back I had a 30 day return window. You might benefit if you can purchase a receiver with the features/power you want and try it out. I can’t think of any better way to determine if that will improve your SQ by upgrading your Yamaha. Even if you do chose to upgrade you could always return what you bought and get something else either from the same place or from the internet. I recently went through 3 HDTVs until I got the one I liked.
Otherwise what besides the “brightness” of the speakers (which I don’t see Audyssey changing much unless it’s room induced and then YAPO should have helped) are you looking to change? IMO Denon sounds no different than other digital amp based receivers I’ve heard.
