Kevin, I'll try to explain my experience. I had the 3805 about a year before I got the 990. I was using the 3805 as a pre amp for the fronts and center; only the surrounds were powered by the Denon.

First, adding separate amps to the Denon made a big difference in sound. Even my wife noticed the difference. Not to sound trite, but it was as if a veil was lifted from the speakers with the amps powering the speakers vs the Denon. 260wpc to fronts and 425 watts to the center.

Anyway, I did not do an A-B comparison; I relied on music that I was familiar with to try to make a comparison. The first thing I noticed was watching "24" in HD/DD 5.1 a few weeks ago. The vocals opened up tremendously with the 990. It was noticeable immediately.

Music was more open as well. Highs had slightly more clarity and soundstage opened up a bit. Again, vocals were more defined and clear in all formats (DVD, DVD-A, SACD, XRCD).

I won't say that I heard things I never heard before though!

Rat, I guess I can say that the 990 did sound better overall. I had a slight hum with the 3805 and had to use a cheater plug (my bad) on the amps. With the balanced connections from the 990 to my amps now I have no noise issues.