I generally prefer to go from the simple to the complex, in trying to solve any problem. Simple is to either move your turntable in your listening room or suspend it, or both. Complex is to add a subsonic filter. If you add a subsonic filter, then a steep slope at a frequency below 20Hz is desireable, but 24db/octave is to be preferred over 18db/octave, because of phase anomalies that may affect upper frequencies. (6db/octave is also good but much too gradual for slope in this case. 12db/octave and 18db/octave are less "good" compared to 24db/octave.) I will bet that moving the TT will solve your problem or at least ameliorate it sufficiently so as not to be a bother.