IMO, a speaker of this sophistication should be carefully positioned using an SPL meter and 1/3 octave tones.
Do this before jumping to the conclusion that your $20,000 loudspeaker is not reproducing bass as accurately as a $3000 speaker.
"Accurate" may mean less, not more bass.
In my experience, bass "slam" is often more substantial from systems that sound somewhat less full-bodied in the low end.
ie: less apparent bass will often sound tighter and more realistic.
Speakers that suffer from doubling effects will have a strong bass response, but will lack low frequency definition.
It's not surprising that the 9NT with it's tiny, wildly flopping woofers tends to sound "bassier" than the more controlled woofers in the 800N. (I own the 9NT and have them rolled-off at 50hz, and paired with a good sub.)
I'm fairly certain that the 800N does not double significantly, and probably has very transparent and highly accurate low frequency reproduction. To my ears, the 9NT does not have particularly clean bass, although it's pretty good for a smallish $2600 speaker.
Powered subwoofers actually make a great deal of sense when paired with well-endowed systems like yours. Rolling off those big 10" drivers below 50hz will only tend make them sound cleaner at high SPLs.
It'll also mitigate whatever low frequency anemia, real or imagined(LOL), that your Adcom amplifier may be imposing. (IMO, Adcom makes excellent amplifiers)
