Goride, check the manual here: http://www.martinlogan.com/pdf/manuals/manual-electromotion-esl.pdf
Your speakers should be placed approximately two to three feet from the front wall, the wall in front of the listening position, and about two feet from the side walls."
I have mine about 2.5 feet from the wall. I'm assuming they mean from the front of the speaker (the panel), not the back box. Perhaps 3 to 5 feet may be optimal, but it's not like they go from spectacular to horrible if they are closer to the wall than that. I believe the main reason you want space is because they are dipole so the sound goes in back and reflects off the wall. I was thinking of buying a couple acoustic panels to put behind them. But then again, they sound great now and the manual also says the surface shouldn't be too soft either:
"The front surface, the wall behind the speakers,
should not be extremely hard or soft. A pane
of glass will cause reflections, brightness and
confused imaging. Curtains, drapery and objects
such as bookshelves can be placed along the
wall to diffuse an overly reflective surface. A
standard sheet rock or textured wall is generally
an adequate surface if the rest of the room is not
too bright and hard. Walls can also be too soft.
If the entire front wall consists of heavy drapery,
your system can sound dull. You may hear muted
music with little ambience. Harder surfaces will
actually help in this case."
The Electromotion ESL for $2,200 is a great buy, just do it!