OK, I get it now.

I think I'm going to wait a few weeks (or months) before really committing to a sub, to really listen to the AAs in a couple different settings and give them time to open up, if they have a break-in period. I'm also a bit hesitant to buy a sub since I have no experience at all with them.

Do you have any recommendations for subs to pair with the AAs, should I decide to buy one?
Also, here's my logic for why I would want to add a sub: the bass on the AAs is low, and it does reach the range I am listening for, which is really nice. However, I like listening to some genres with a bit more power in the mid-lower end, probably in the 50-100 Hz range (not rap music 30 Hz stuff). I found that giving a slight bass boost on the NAD gives me more of the sound I want, but I worry that bass boosting a bookshelf speaker will put unnecessary wear on the woofers and a sub would be a better way to go. Is that reasonable?