Wow... it doesn't usually work out that nicely...

I don't think there are a lot of alternatives to moving the speakers, unfortunately. If the frequencies were higher you could just put something absorbent on the wall, but AFAIK you need at least a few inches of fuzzy stuff to absorb as low as 250 Hz.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8