What is a sympathetic resonance?
Check your room for the following items: acoustic guitar, glass, chair, bookshelf, lamp, windows and what not… all of those can have a sympathetic resonance and you most probably won’t enjoy that sound that resonates to the sound coming from your speakers.
Most DAWs have tone generator plug-in. Crank the volume up and sweep a sine wave from low frequency to the top and identify items/sources that vibrate and gives that nasty noise.
Now that you know the sources, burn them with a flamethrower, seal them, put in the closet… just do whatever it takes to make sure nothing vibrates or moves!