So I just bought a Hegel H390 and

Amazing amp!!
congrats. Will deliver years of musical bliss. 
   Looked at Hegel years ago, I was turned off by the “stuffing” of so much in the stereo amps, caps, wiring, VA torroid , etc. 

   Hegel is great stuff.

plenty of power for hundreds of great speakers. 
   Would take the suggestions on Dynaudio, they are amazing. Only reason I didn’t go Dynaudio is it was only a few hundred more than what I bought. 
  Enjoy, you made a great mp choice for sure!!

 Report back after your ears are accustomed to her.  

Hello,
The Hegel products have a really good damping factor. If a typical amp would have say 1000 damping factor I believe this amp has 4000. It’s amazing how even their smaller amps like the H95 can drive Maggie’s. This H390 is second from the top so it can do it with ease. 

Okay you erred by buying the INT ahead of the speakers but you
made a great choice so you're not boxed in.

The most musical sounding Speaker we heard at a recent event was the
Sonus Faber Electra Amator 3. Fits your price range. 
In a smaller room a 3 way might not work. That speaker is one of the sweetest sounding I've ever heard. Quit reading now and buy it!

In your 15 x 15 room consider headphones or at maybe some
LS 3/5s in near field configuration. Or just save your money.

My friend has the H390 paired with the new Dynaudio Heritage and its absolutely sublime. A few other people have this exact combination and their feedback tends to agree.

I am not sure if its the amp or speakers, but it’s slightly, and I mean slightly, to the warm side of neutral. The presentation is a bit laid back (but not dull) and completely natural and coherent. You can listen to a lot of music on this combination without fatigue.

Before getting the Heritage we auditioned the almost twice as expensive Confidence 20 with Moon amplification. A totally different sound, more hi-fi, and IMO not very good at all. Maybe it was the Moon gear and not the Confidence 20, but I did not like it and thought it way overpriced.

But some Dynaudio fans have been saying they like the new Heritage better than the Confidence, so it could be Dynaudio have voiced this speaker for certain tastes.

i would agree the h390-590 are voiced slightly on the warm side of neutral (but without tube-like midrange ’bloom’, just smoothness and luscious tonality), and the treble is definitely on the restrained side but still with excellent detail and vivid spatial representation, heard through a deep dark background (similar sound profile as pass and ayre, but hegel does bass better than ayre imo) ... thus folks with highly resolving systems seeking a more natural (rather than a ’super hi fi’) presentation love the hegels