Update 5/22/2012

Overall I continue to be pleased with the sound quality and volume of my system due in no small contribution to the performance of the DEX P99.
The image is set- I find no need to adjust TA any longer. Thanks to those who suggested to go for it, once you record the settings it is quite easy to run through the menu and make additional refinements.

I am not quite satisfied with final tonality of the autotune EQ portion. Even manually adjusting the EQ is kind of like shooting in the dark.
I have hardware on order to do some real time analysis and I am anxious to see the response of my current tune as well as the (hopefully) improved SQ once I know where the hot frequencies are boosted / reflected. Switching off the auto EQ reveals a very hollow, bassy sound so I know there is plenty of midrange / upper midrange boosting occurring from the autotune EQ results.

An observation of a particularly nice touch is that the audio menu always returns to the place you left off when you select it. This is helpful when tuning on the run, say you make an adjustment to the tweeter level, play it for a few miles, you can easily and quickly get back to that menu just by entering the audio menu and re-adjust as necessary. I'm sure this has led to arriving at a more refined tune in a shorter amount of time.