Image/soundstage and punch/bass

IMO you're asking for a lot at $2500.  Subs are the obvious choice, but if that's not your bag these Nola Vipers might be a good choice.  Bass down to 28 Hz and mids and tweets are dipoles like the Maggies that may appeal to you from an imaging perspective.  At $3500 they're a bit over your price, but as I said you're asking for a lot, and these were originally $8000. 

https://www.usaudiomart.com/details/649497865-nola-viper-ii-plus/

Add two good musical subs like the Rythmik 12” or 15” sealed. That will fall within your price range and should integrate well with your Maggie’s keeping the “air” and delivering the punch!

I paired two of the Rythmik F18’s in a rather large room with BG Radia FS-420i planar ribbon speakers and the difference was startling.

www.rythmikaudio.com  

I have a pair is Magnepan 1.7i and run occasionally an older Paradigm or Snell subwoofer with them. That is about as good as you are going to do for $2200 for the Maggie’s and the rest on a subwoofer. As for the Dynaudio’s: I had been a big Dynaudio fan. That ended when I heard these Magnepans. They replaced my Dynaudio Contour 20s. I’ve heard the Special 40s. But I am sorry. They are not going to cut it against the Maggie’s. I have to say that at $2200 the Maggie’s are the biggest bargain in speakers today. I am waiting for my Mye Stands to come and the Bass should tighten up further. 

You might consider a pair of Magnepan DWM's, about 1700 or so for the pair.  200 to 40 hz to augment the MG12's.  Add 1 sub or two if you can.  I use 2 10s and a 12 to pressurize the room about 65hz.  IMHO opinion this helps the maggies bottom a lot.

Man, I didn’t know ET was still around, let alone making speakers. I have a bunch of Rythmik subs here, but the ones in my main system--- a pair of sealed 15" are crossed over pretty low- and "punch" to me, is more upper bass, not just deep bass. How high do you run these Rythmiks out of curiosity?