Turntable feedback rumble problems with new sub

I have a Technics 1200 M3D and KEF LS50s. No issues. I just added a REL T7i and have a runaway feedback rumble problem at high volume. I added Isonoe footers to the table which didn’t do much. Unfortunately the table and speakers sit on a big media cabinet from Design Within Reach which is not ideal.  Not sure what the right next move is.  More turntable isolation, put footers under the cabinet legs, new turntable, new furniture, or new house?