One thing to double check in the mean time, is to make sure when using Dirac, with something like a Umik-1 mic, use sampling frequency 48 kHz, if you use 192 kHz, you will have high frequency roll off very early, though dropping off beyond just 100 Hz should only happen with subwoofers.
The X3800H is really a value king, but keep in mind you would have to spare another $500-$700 (with bass control), depending on the Black Friday discount that is expected, based on history, it could be as little as 20%, or as much as 33%. They now also have ART working, but you likely can do well enough with just the bass control license. Audyssey MultEQ Editor can also get you great result, but it might take you hours of work to get the flattest/and smooth bass you can get if you are a near perfectionist, otherwise within a few hours should get you something like +/- 3.5 dB between 20 to 150 Hz, then you can add a bass tilt to your taste. That app costs $20.
