Armoire between speakers

It really only effects soundstage/imaging, so if that quality is not the most important to your music reproduction experience, then don't sweat it.

Keep in mind that a reflective surface well behind the plane of the baffle will reflect some bass rolloff to the sides where you aren't. Unless you are, in which case you should move back to the sweet spot and stop looking out the window at the inappropriately young neighbor chick or stashing jewels and sacred setup documents from Mapleshade in your wall safe. The imagined soundstage has an effect on the actual one created by the system, so there's that, but otherwise trust your ears and only your ears (never "comprise" the sound), or merely glue 4 inch thick foam rubber to the armoire and paint a tromp l'oeil vista of the Vienna Opera House on it.

Did you just recent get this armoire ?

Bizango.....I'll bet your fish are big fins of Handel?

Magfan,
Lemme guess, Water Music? You should come over to listen and drink.