Hi Bro,
The boomy bass that you are experiencing with both movies and music is due to the room primary mode peak. Based on room dimensions, it is likely in the 35hz range.
Using the PEQ in your yamaha processor, try applying a high Q cut (Q of 5 or even higher) at 35hz range ( try 34, 35, 36 Hz etc ) up to 6-8db cut. Not too familiar with the yamaha, if can apply for both subwoofer channel as well as front LR channel for stereo.
You should be able to hear the difference clearly once the cut addresses the main modal peak.
Let us know if this works.
Amazing MBL speakers and electronics !! Superb!!