I agree it's a tough choice based on the specs. The Denon has 7.1 vs 6.1, plus the extra 10 watts per channel. But the Onkyo has 192khz/24bit DAC's compared to the Denon's 96khz/24bit DAC's, and the Onkyo also has THX processing and more digital inputs.
The Onkyo website doesn't offer much information about their products, so there are a couple of things I can't determine: 1) Does the Onkyo have something similar to the Denon's 5/7-channel stereo (ie multi-channel without dsp effects). Also, what are the crossover options of the 797?
Ian, you mentioned the extra power of the 3802 as a factor. Given the speaker setup Joe mentioned (which is what I am also considering), how much of a real world difference would the extra 10 watts p/c make? After all, you have to double the wattage to get a 3db increase, right?
