Advice

[RebelMan]

I should not say it but the order of magnitude improvement you can make is: room treatment > changing your speakers > moving to a 250.

Jean-Marie

So there you have it; Set up> Room treatment > Changing speakers > move to 250.

Never in my wildest dreams did I think set up could be so good that room treatment becomes less important.

Yes you are right. I had hastily lumped together setup and treatment, but you are right, treatment comes only after you have a good setup. 

And a good setup can do wonders, especially by reducing the impact of the room if you are listening in near field or quasi near field. 

By the way, near field is a great solution if you have a difficult room that you cannot treat for any reason. 

Jean-Marie

Actually, you cannot have a proper setup without a well behaved room.  So, I concur with your first assessment that setup and room treatment go hand in hand.  That said I would reverse the order and put speakers first.

i.e.  changing speakers > setup and room treatments > move to 250

Why?  Because speakers exhibit an acoustical character, a flavor of sound if you will.  Setup and room treatments do not.  Proper setup and room treatments improve imaging and sound staging and are sterile, meaning there is no acoustical character in the process.  Nearfield listening, as you suggested, proves this and is sage advice for those with systems in more challenging situations.