The Onkyo is a THX Ultra system, and currently has ProLogic 2, DTS-ES (or is it EX, or both?!) and DTS Ne0 6.1, and is fully upgradeable for more. It sounds amazing, although I haven't directly compared it to the Denon.

I would guess, too, that models manufactured since last summer also have the "fan" problem fixed: the original setting for the fan was way too high, causing it to be audible when soundtracks are very quiet. And there is a hardware fix available for free for older units.

It is a truly powerful and pure sound, and the setup menu lets you customize it to death. ... Mike