Soundproof Insulation Queston

I will be moving into a new home, a Semi-Detached home. Let me describe the stereo room for my question. The room is rectangle and the stereo will be centered on one wall. The right side wall is the wall that is attached to the other home (my neibour). Behind that wall there is soundproof insulation and concrete block. On the other wall, the left side wall it is just normal construction without insulation. My question is will there be a degration in volume on the right speaker (being next to the insulation wall). Will my center image now be off? Or should it not make a big difference because the insulation is behind drywall?

Thanks a bunch,
The insulation changes the Q factor of the wall and reduces it somewhat. Thus it's resonance characteristic will be milder on an insulated wall vs a non-insulated wall. What is probably of a greater concern is the concrete behind the wall. This will stiffen up that entire wall and thus the energy reflected off of this wall will be greater than that of the opposing wall. Fortunately, most of the difference will be in the lower frequencies where an imbalance is less noticeable. If you wanted to balance out the two walls, double sheetrocking or soundboard and sheetrock would likely come reasonably close to a balance. I would listen first, and see if you find the mild imbalance problematic or not.