Just wanted to thank you all for the tips regarding which Denon to look at as replacement for my old AVR-3600. I brought a 1910 and a 2809 home from Best Buy yesterday and spent the afternoon A/B-ing them both with my 3600. Since my speakers can be bi-wired, I was able to use an old video game switching box to flip between the receivers with basically one click.
All my tests were done using CDs, listening in 2-ch stereo mode. I used one song off American Beauty by The Grateful Dead and a couple of songs off Who's Next by The Who in my comparisons.
All the tone controls were flat. I didn't run Audyssey on either receiver, since I didn't have a mic, but I did make sure the mains were set to small, crossover at 80hz, and set the dB plus / minus of each channel equal to the levels on my 3600 from whenever I last attempted to calibrate it using an SPL.
Anyhow -- the 1910 was significantly more harsh than my old 3600. For lack of a better word, there was a smoothness to the sound the 3600 was putting out that was simply lacking in the sound from the 1910. At louder volumes, the 1910 sounded almost harsh and fatiguing in comparison. It's entirely possible that some of the EQ magic from Audyssey could have helped -- my living room certainly isn't an ideal listening environment...
I asked my wife -- who enjoys music, but isn't as critical about it as me -- to do a blind comparison of the two, just to make sure I wasn't pooh-poohing on the cheaper unit, and she had a similar reaction; the 3600 was much more enjoyable than the 1910.
The 2809 was a much more balanced listening experience, right out of the gate. In fact, I think it had a bit more clarity in the sound than my 3600. Bass seemed less boomy, and the acoustic guitars and harmonies in songs like Behind Blue Eyes and Box of Rain seemed even more clear than on the 3600. We re-ran the blind listening test with my wife, and she thought they both sounded great, but actually picked the 2809 over the 3600! We had a winner!
I'm hopeful that after calibrating the 2809 with Audyssey and so forth, it will sound even better.
I just wanted to get the info out there for anyone who might be wrestling with the decision of which receiver to buy. 2809s / 989s can be found for between $250 and $400 more than 1910s, depending on if you're comfortable buying refurbs or not. Happy hunting! And thanks again for the advice!