Where to place the speakers?

[Limtre]

The only active speaker I know that has built in adjustment (but no auto room correction) for this kind of problem is the Kii Three. The Kii Three is even more 'a speaker' than LS50... and the price is twice that of Phantoms.
Room correction does not necessarily mean more boxes. Acourate or Audiolense would fix most of the issues of your current plan. You'd need a player with convolver capabilities like Roon or JRiver and you will still keep your setup with only a laptop and Phantoms. Sources directly connected to Phantoms/Dialog would still have the problem though.

OK, thank you for a good and accurate answer

The thing is that I like the speakers very much, but I've found out that it's really important to get a good position. 
From what the seller at the store told me it wasn't as important with these as ordinary speakers.

I guess I'll find out as soon as I've spent some time with the setup once I get the new apartment.
Worst case scenario; I'll get another setup :-)