Proac D48R

I recommend you to change the stock metal jumpers for better quality ones as soon as the speakers arrive to you because they do degrade the sound severely also Proac speakers are known for their very long burn-in period allow about 500 hours before fully break in( it is also mention at their user manual). 
You made the right choice please keep us update for first impression. 

I would consider pre plus power (not integrated) of Macintosh or Bryston for the D48R ,it will cost you more than 5K for new but for speakers that cost around 10k do deserve better amplification maybe you can find better options in your budget at the used market than you can consider Pass lab,Audio Research, Krell,Classe act  as well .

Try to move one of the speakers little bit forward than the other it seems strange but it did miracles at my room with my Proac's the right speaker is more forward to my position listening than the left one the soundstage became more focused and transparent. 

Email Straight to Proac and ask them.

What you are describing is relevant for almost any speakers I called it ’screening’ affect ,when you are hearing the speakers with the grills on it like you are putting a screen between the twitters and drivers to your ears .The grills are for to protect your speakers from dust or potential damage to the speakers’ components.