Ok, now I'm envious as I've ran out of space in my cabinet \:\) .

Try making an equilateral triangle between you and the speakers. It should improve imaging. Failing that, moving them further away from the back wall should also improve imaging. The angled walls will help with imaging too because, depending on the geometry of the rest of the room, you likely won't have first reflections to deal with.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated