I've found the imaging of the SP16 to be quite precise and capable of a very wide soundstage. I'm at a loss as to why you would find it "too mono".
Just read your followup - sounds like speaker positioning may be your issue. Might be difficult to achieve a wide soundstage under those circumstances. Speaker positioning and proximity to walls etc will have a greater effect on imaging than (competently designed) electronics.
Just read your followup - sounds like speaker positioning may be your issue. Might be difficult to achieve a wide soundstage under those circumstances. Speaker positioning and proximity to walls etc will have a greater effect on imaging than (competently designed) electronics.