Thanks to everyone who has provided info to my various posts recently. Greatly appreciated. In return, for what it's worth, I thought I'd tell you all my experience testing the Yam 2500 v the Denon 3805 today with both music and a movie (Lord of the Rings battle for Helms Deep).
In short, I have decided to go with the Yam 2500 (acutally the 2600 when it comes out, but the overall sound review should be the same for both).
Why?
On music the Denon was a little bit better balanced with highs and lows, while the Yam seemed a little "bright", as most of you probably already know. However, the Denon's better "balance" almost seemed like it was muddled, especially in the movie. Anyway, with the addition of a subwoofer during 2 channel music listening, the Yamaha's brightness problem was a non-issue.
The real decision happened when I watched the battle for Helms Deep. The Yam was CRYSTAL clear and was much crisper across the board. Lightning strikes were razor sharp and you could nearly hear each individual rain drop on the armor of the orcs. It was amazing....I guess that may have something to do with the THX, but who knows. Alternatively, while the Denon was generally fine for the movie, it was perfectly clear to me that it did not sound nearly as crisp or detailed as the Yamaha. The rain drops that I had heard with the Yamaha were almost non-existent. You could hear them, but they were one big sound as opposed to the crispness of individual rain drops, if that makes sense. The Yamaha just did such a superb job on the movie that I can overlook its "brightness" on the music side (especially with the addition of a subwoofer for 2 channel music).
Anyway, this is just my personal experience and I am very much an admitted novice at all of this, so take this with a grain of salt. I am just trying to put into words what my ears heard, and I think that is the best analysis for my purposes. I don't want to start an argument of Denon vs. other brands. I thought the Denon was good, but the Yam just blew me away so well in the movie that I am going to buy that product. And, thought you all might enjoy my (very very novice) review of these products.