My apologies for taking far longer than the "ten days or so" to post my initial thoughts on the Onkyo TX-NR709.
I'm really enjoying it. Connection to my Rotel amp was simple. Calibration was also very easy. The unit bumped up the surrounds a bit higher than I would prefer, went into the manual adjustments and toned them down to my taste. The Onkyo added a slight 40hz filter to my three front speakers, I called Definitive Technology just to double check that running them as "full" was fine. The service rep at Def Tech confirmed the "full" mode (and reminded me that if I play music in any kind of 5 channel stereo mode I may want to put the 40hz filter back on my center channel). Running the three fronts as full really brought them to life.
My only complaint is the over abundance of surround modes. My old Chiro pre-amp played multichannel movies directly or with THX mode to tone down the high end. Stereo music was simple two channel or "enhanced", which sent a slight signal to the surrounds. The Onkyo has a perplexing amount of surround modes such as Theater-Dimensional, Neo:6, Neo:6 Cinema, Neo:6 Music, Orchestra, Unplugged, TV Logic, Game-RPG, Game-Action, Game-Rock. Same with the never ending amount of volume modes such as Dolby Volume (on/off - "automatically adjusts the difference in volume levels which can occur between different contents or source components"), Dolby Volume Leveler (off/low/mid/high - "maintains the perceived loudness of all contents, coming from different channels or input sources."), Dolby Volume Half Mode (off/on - "Dolby Volume applies a bass and treble attenuation to the audio when the system gain exceeds reference level."), Audyssey Dynamic EQ (off/on - "enjoy great sound even when listening at low volume levels"), Audyssey Dynamic Volume (light/medium/heavy - "This setting affects volume the most. It quiets the loud parts, such as explosions, and boosts the quiet parts so they can be heard"), THX Loudness Plus volume control technology ("enjoy even subtle nuances of audio expression at low volume", and last but not least IntelliVolume (set in 1 dB steps - "set the input level for each input selector individually"). Frankly, I'm simply turning all this stuff "off" and setting the unit in "Direct Mode". I wanted a pre-pro that would finally let me hear my blu-ray's in DTS Master Audio and Dolby True HD. In Direct Mode the 709 does just that and I'm extremely pleased.
Thanks again to all of you for your input.