Hmmm, maybe I'm just an idiot and should do what I think sounds good to my ears???
Bingo. Well, except for the idiot part. You're only an idiot if you get swept up into the 'keep spending excessive money for negligible gains' camp. Don't be afraid to use your tone controls if it sounds better to you. Your 2100 is capable of about 200 clean watts, so you shouldn't run into trouble. You would only benefit from getting the 2200 or 2400 if you are really pushing the spl limits. That old 2200 I had killed my first pair of paradigms (actually ripped apart the spider and completely dislocated the voicecoil from the woofer), so watch out if you go that way.
Back when my 2100 was being used as the primary amp in the living room system, I was sharing a house with musicians who had several different eq's and processors laying around, and of course I had to experiment. They used BBE sonic maximizers for dead-sounding venues. Used in the home, that processor could provide the impression of fatter, deeper bass, I would say more subjectively satisfying than simple tone controls. They are cheap as hell from your local guitar store, fyi. If you're not signal-purity obsessive, this may be a legit, cost effective route to greater satisfaction for you. It worked for me for quite a while, at least until I got into the SET thing. (When it comes to fooling your brain into believing there is a drum kit and stand up bass actually present in your listening room, nothing can match the detail, punch, and drama of a SET paired with efficient speakers. Keep in mind I'm from the subjectivist, live music as the metric camp, not the measurement, IEEE document, oscilliscope camp.)
If I were you, I would utilize my sub and consider adding a second for more even in-room response. Getting the 2200 or 2400 would only help marginally; perhaps you would consider more efficient speakers in lieu of getting vintage NAD gear, or if you want the power get something new (pro-audio amp or Emo, new with warranty are both cost effective choices). You could try a processor as I suggested above. And play with your room (speaker placement, decor/treatments have about as dramatic an impact on sound as the equipment, and if you go spending money on expensive gear before optimizing your room you've veered into that 'idiot' realm).
Good luck achieving audio nirvana. Let us know how it goes.