Best bookshelf speakers for McIntosh MC275 amp?

As I move into the new appartment next month I decided to separate my current HT/music system into dedicated HT and stereo systems. The living room is a 68 square meters studio while the "musical" room is just 16 square meters and it's perfectly square in shape. So my floorstanding Sonus Faber Grand Pianos obviously stay with the Home Theater in the living room while I will need bookshelf speakers for my Sony XA9000ES - Pre (not yet decided ) - McIntosh MC275 power amp. The budget is between $3000-5000. What I need is open, dynamic and natural sounding speakers that dissapear as you close your eyes if that's possible. Any suggestions?
Unfortunately or luckily, there is no "best" anything. It's all relative.

You don't say if your budget is for new or used. If used, I would suggest the Focal (JM Lab) Micro Utopia Be. Stunning speakers with surprising bass and small size. If new, I would suggest the B&W 805S. Both fit your sound criteria, will be well accomodated in a 16m2 room, and are very synergistic with McIntosh amps.

sterling, harbeth, gradient, AE, totem, mcintosh, and about 200 more. the mc275 can make any decent speaker a pleasure to listen to.
What sounds best to you. I like the Micro Utopias. They were much more accurate than the Mini Utopias that cost more back in the days before BE's.