Looking at your room, my first reaction is that the phenomenon is perhaps associated with the open area to the left of the speaker. My guess is that you are hearing the sound of the driver without the first reflected wave off the side wall, and that it becomes noticeable/irritating at certain frequencies. I presume the phenomenon is there independent of listening level.
If you are desperate to find out, you could perhaps rig a blanket or two over the opening to see if the annoying sound is ameliorated.
Try doing a frequency sweep and see if the annoyance is still there in one channel. If not, then it’s not the gear.
If you are desperate to find out, you could perhaps rig a blanket or two over the opening to see if the annoying sound is ameliorated.
Try doing a frequency sweep and see if the annoyance is still there in one channel. If not, then it’s not the gear.