Dynaudio X12 upgrade

Hello to all
I presently enjoy Dynaudio Excite X12 which are quite good, but IMHO the weakest point in my setup. Thinking about Special 40, but not quite sure are those going to be adequate. I really like Dynaudio house sound (or lack thereof), but I need a speaker which can deliver Orff's Carmina Burana and Pink Floyd's Echoes with the same grunt and finesse on lower as at higher SPL. So, before I start creeping around dealers and lugging speakers to my home, I thought to ask for a opinion(s) here.
My amplifier is Bel Canto S300iU, and I'll try to paint the picture like this: Low SPL right now is up around 50; X12 finally coming to life around 60; unity gain is at 80 - and X12 start clipping... If they could talk, they would start cursing around 75. 
I would like to stay with Dynaudio monitor. I do not think my room is big enough for C20, and I heard from others C1 Platinum is far better than C1 MKI (which I heard, driven by Moon) and can be perfectly happy at lower SPL, in a room of medium to small size, like mine (~400 sq. feet). Would it be good to save more money for C1 Platinum, or Special 40 would be "just the ticket"?
I appreciate all, but comments from owners who compared all three speakers would be the most welcome. 
Rest of my system:
Pink Triangle One / Nottingham Ace Space 9" / Ortofon Quintet Black into EAR 834P (primary)
Magnum Dynalab MD801 (background and news)
I would attach the photo of my setup, but I don't know how... Also, I apologize for my English, for it is not the best.

I am a big Dynaudio fan. With that said, the special 40 had a poor wrtite up in stereophile recently due to box resonance, which quite honestly is puzzling and completely unacceptable for any decent speaker, never mind a Dynaudio.  

X18 gets you into esotec drivers which are a step up from the x12 and 14. 

What I use is the Focus XD 20/200 which I bet you would love,  but it would mean big system changes. 

You could also consider Revel and and KEF, which are phenomenal and very well designed. 
Thank you for your suggestion on Revel and KEF. I used KEF, old and Uni-Q, but both are not "my cup of tea", for various reasons. Ever since I bought X12 and later heard C1 at the same dealer, I am thinking about upgrade. Maybe it would be better to save up for C1 Platinum (even gently used) than buying Special 40 and getting disappointed... 
Listening Jethro Tull right now, Living In The Past double LP, good old Chrysalis pressing. Nice evening, and I want quiet but great music. By the way, not audiophile wet dream recording, but amazing considering the time when created. I just need that "little bit" that I get when volume goes up. Kick drum and snare are there, with that natural compression of the hit, but no weight I heard on C1.
Or, I'm idealizing, trying to find a reason for upgraditis neurosa...
My Dedicated listening room is approximately half the size of yours. I had used the Ascend Sierra 1’s, but always wanted to try a Dynaudio product. When I purchased my Dynaudio DM 2/7’s the increase in slam, impact and dynamics was startling. In comparison, the Dynaudio bookshelf’s have much larger mid-bass driver over the Ascend’s. The previous suggestion to move up to the X18’s might give you the changes your looking for. Have you also considered the the Excite X34’s?