upgrade Dynaudio Special 40 to Kef Reference 1

Kef and Dynaudio sound totally different, in general. I prefer Dynaudio sound but that’s just me. Dyn’s are typically harder to drive (more difficult impedance curves, lower sensitivities). Kef is good too though, especially if it is important to you that the entire room sounds pretty good, as opposed to being optimal in one listening location. Kefs might be better than almost any other brand in that feature. Really good choice if H/T a part of your system and whole family watches movies together, for example (foregoing not at all to suggest Kef not good for music, it is as well).

After owning all the above mentioned I would buy Piega coax 311. 
A keeper 

You need to drag your amp to some stores and LISTEN.  Only then can you tell whether there is truly and improvement or not, and whether that improvement is worth it in monetary terms.  Everything else is scratching a mirage-like itch.

Kren’s point about KEF Providing more consistent sound from different listening points than most including Dynaudio rings true from my experience with Dynaudio Contour monitors versus KEF ls50. The Dynaudios were very good but seemed to require more care in exact positioning as well. Dispersion with the KEF UniQ driver seems top notch. I often listen from my desk located between the two speakers and the KEF ls50s retain their character particularly well even there.

dynaudio require power power power and more power big transformers ,heavy amps:) this hegel offers not so much, Yamaha AS3000 looks nice,but again no real power
If you get decent powerfull amp,the sound will be as listening gryphon and big speakers in your room:)
Not sure abaut your bugdet ,but there is big krell fbi for sale
I think even krell s550i will outperform hegel and yamaha and will make your special forty sing