Looks like Shadorne has already given you all the bad news. You can only reduce the effect but it won't go away entirely.
In many of the audio rooms I have measured, a suckout between 55 and 80Hz is very common but can be reduced by sitting closer to the back wall (i.e., farther from the speakers). Give that a try first since it is generally easier than moving speakers. Sometimes it only takes a few inches to make a noticible difference. The downside to doing this is that lower bass will get amplified but that may not be a problem - or at least not as much as the suckout. Can't win them all anyway.
Arthur
In many of the audio rooms I have measured, a suckout between 55 and 80Hz is very common but can be reduced by sitting closer to the back wall (i.e., farther from the speakers). Give that a try first since it is generally easier than moving speakers. Sometimes it only takes a few inches to make a noticible difference. The downside to doing this is that lower bass will get amplified but that may not be a problem - or at least not as much as the suckout. Can't win them all anyway.
Arthur