Being close to the back wall does not have any direct correlation to increasing soundstage with a monopolar speaker. And with a dipole, bipole or omni, it would simply be disastrous. But placing a monopole this far into the back of the room like that with the listening position so far away will ensure that you hear a dominate level of ambient/reflected sound, drowning out the direct sound. If you move them farther away from the wall, say, within 6-7' of you and 4' from the wall, and with a much wider spacing, the sound quality should improve dramatically, with reduced room influence(which you really want to reduce with a speaker like this). Adjust toe in for best imaging. Now, you are left with the fact that if this was designed to be close to a back wall, then the baffle step compensation will not be sufficient on the speaker when placed out into the room. You can correct this with a precision EQ that has a shelving filter function, such as a Behringer DCX2496. You simply calculate the 1/2 wavelength distance of the front baffle, then enter a low shelving filter in the DSP EQ of this frequency, with a 6db/octave slope. Then increase relative level of this correction curve until the lower mid-range and mid-bass is at the appropriate level. If you can not move them as specified, then substantial acoustics treatment is highly recommended. Right now, I believe the SQ potential of those speakers is not being met.
-Chris